PIK3CA-related disorders are rare genetic disorders due to somatic gain-of-function mutations in PIK3CA during embryonic development, a pathway involved in cell growth, proliferation, and metabolism. Accumulating evidence from patients with PIK3CA-related disorders indicates that peripheral nerves are frequently affected, leading to severe neurological symptoms. However, the exact underlying mechanism of these disorders remains unclear. To address this, we developed a mouse model with a PIK3CA gain-of-function mutation specifically in Schwann cells, which successfully mirrored the clinical features observed in patients. In this model, we observed that PIK3CA-mutated cells communicate with neighboring healthy cells, such as adipocytes and hair follicles, through a unique crosstalk mechanism that triggers their growth, proliferation, and anagen phase expansion. Additionally, we demonstrated that PIK3CA mutation in peripheral nerves leads to a metabolic shift through glycolytic activation. We investigated the effects of alpelisib, an approved pharmacological inhibitor of PIK3CA, in the model. Early administration of alpelisib significantly improved the signs and symptoms in the mice. However, when treatment was delayed, its efficacy was diminished due to the drug's inability to penetrate the myelin sheath effectively. In summary, our study offers a valuable mouse model for studying PIK3CA-related neuropathy, uncovers a unique communication between healthy and affected tissues, and highlights the potential benefits of early pharmacological intervention using alpelisib.

Abstract Accurate melanoma diagnosis is crucial for patient outcomes and reliability of AI diagnostic tools. We assess interrater variability among eight expert pathologists reviewing histopathological images and clinical metadata of 792 melanoma-suspicious lesions prospectively collected at eight German hospitals. Moreover, we provide access to the largest panel-validated dataset featuring dermoscopic and histopathological images with metadata. Complete agreement is achieved in 53.5% of cases (424/792), and a majority vote ( ≥ five pathologists) in 90.9% (720/792). Considerable discordance is observed for non-invasive melanomas (complete agreement in only 10/73 cases). The expert panel disagrees with the local pathologists’ and dermatologists’ diagnoses in 14.9% and 33.5% of cases, respectively. This variability highlights the diagnostic challenges of early-stage melanomas and the need to reconsider how ground truth is established in routine care and AI research. Including at least two pathologists or virtual panels may contribute to more consistent diagnostic results.

Hemifacial myohyperplasia (HFMH) is a rare cause of facial asymmetry exclusively involving facial muscles. The underlying cause and the mechanism of disease progression are unknown. Here, we identified a somatic gain-of-function mutation of PIK3CA in five pediatric patients with HFMH. To understand the physiopathology of muscle hypertrophy in this context, we created a mouse model carrying specifically a PIK3CA mutation in skeletal muscles. PIK3CA gain-of-function mutation led to striated muscle cell hypertrophy, mitochondria dysfunction, and hypoglycemia with low circulating insulin levels. Alpelisib treatment, an approved PIK3CA inhibitor, was able to prevent and reduce muscle hypertrophy in the mouse model with correction of endocrine anomalies. Based on these findings, we treated the five HFMH patients. All patients demonstrated clinical, esthetical, and radiological improvement with proof of target engagement. In conclusion, we show that HFMH is due to somatic alteration of PIK3CA and is accessible to pharmacological intervention.

To the Editor: Currently, pathologic melanoma classification is based on the—inevitably somewhat subjective—integration of several histologic features.1Adamson A.S. Welch H.G. Machine learning and the cancer-diagnosis problem–no gold standard.N Engl J Med. 2019; 381: 2285-2287Google Scholar Thus, discordance between pathologists classifying the same lesions can be substantial, and objective assistance tools are needed. The classification of dermoscopic skin lesion images based on convolutional neural networks (CNNs) works well.2Tschandl P. Codella N. Akay B.N. et al.Comparison of the accuracy of human readers versus machine-learning algorithms for pigmented skin lesion classification: an open, web-based, international, diagnostic study.Lancet Oncol. 2019; 20: 938-947Google Scholar On a histologic level, our pilot studies provided a proof regarding the principle of CNN-based melanoma recognition using tiny sections of hematoxylin-eosin–stained digitized slides.3Hekler A. Utikal J.S. Enk A.H. et al.Pathologist-level classification of histopathological melanoma images with deep neural networks.Eur J Cancer. 2019; 115: 79-83Google Scholar,4Hekler A. Utikal J.S. Enk A.H. et al.Deep learning outperformed 11 pathologists in the classification of histopathological melanoma images.Eur J Cancer. 2019; 118: 91-96Google Scholar We compared the ability of CNNs with that of 18 international expert pathologists from eight different countries to discriminate melanomas and nevi in a less artificial setting using hematoxylin-eosin–stained whole-slide images. Ensembles of 3 individual CNNs were trained and tested using single hematoxylin-eosin–stained whole-slide images of 50 individual melanomas and 50 nevi labeled by a panel of 2 experienced dermatopathologists according to the standard practice to provide the “ground truth” (Supplementary Figs 1 and 2 available via Mendeley at https://data.mendeley.com/datasets/j87c9jshxy/1, Supplementary Table I available via Mendeley at https://data.mendeley.com/datasets/j87c9jshxy/1). The same 100 digitized slides were diagnosed using a web-based survey by 18 international dermatopathologists, each with at least 5 years of experience. With respect to the ground truth, the 18 individual pathologists achieved a mean sensitivity, specificity, and accuracy of 88.88% (SD = 6.66%), 91.77% (SD = 3.99%), and 90.33% (SD = 4.52%), respectively. Ensemble CNNs trained using slides with or without annotation of the tumor region as a region of interest performed at par with the experts (Fig 1) in terms of mean sensitivity, specificity, and accuracy (unannotated: 88% [SD = 0.0%], 88% [SD = 1.15%], and 88% [SD = 0.58%], respectively, and area under the curve [AUC] 0.95; annotated: 94% [SD = 0.0%], 90% [SD = 2.31%], and 92% [SD = 1.15%], respectively), with an AUC of 0.97. Majority of the votes of the expert panel yielded the best accuracy (98%). A statistical analysis of the performance differences is shown in Supplementary Table II (available via Mendeley at https://data.mendeley.com/datasets/j87c9jshxy/1). Only half (47%) of the diagnoses were unanimous. Overall, the discordance was 13.45%. Nine lesions were divergently classified by a third or more pathologists. Two were classified divergently based on majority (Fig 2, Supplementary Table I), of which 1 was originally classified as severely dysplastic acral nevus and the other as incompletely excised desmoplastic acral Spitz nevus with the melanocytic acral nevus with intraepidermal ascents of cells phenomenon, both of which the ensemble CNNs classified as melanoma. The diagnoses by ensemble CNNs trained using unannotated and annotated whole-slide images differed from the ground truth in 12 and 8, respectively, often pathologically unequivocal, cases. An ensemble CNN, trained and tested using an independent set of slides with the same methodology to confirm its reproducibility, achieved a mean sensitivity, specificity, and accuracy of 98% (SD = 0), 88% (SD = 0), and 93% (SD = 0), respectively, with an AUC of 0.97. Thus, a high-accuracy classifier can be generated for a specific test environment with few images. Although such classifiers may not yield similar performances on slides from another institution,5Niazi M.K.K. Parwani A.V. Gurcan M.N. Digital pathology and artificial intelligence.Lancet Oncol. 2019; 20: e253-e261Google Scholar the practical application of environment-specific assistance tools may be more realistic than an attempt to achieve broad generalization across all environments. Such systems might be the most beneficial for less experienced pathologists. For experienced pathologists, the systems could provide a triage.5Niazi M.K.K. Parwani A.V. Gurcan M.N. Digital pathology and artificial intelligence.Lancet Oncol. 2019; 20: e253-e261Google Scholar Further studies are required to investigate CNN-based classifiers in a real-life setting. Dr Brinker would like to disclose that he owns a health technology company (Smart Health Heidelberg GmbH; https://smarthealth.de), which develops mobile apps, outside the submitted work. Dr Beltraminelli would like to disclose that he received honoraria for his role on the Takeda Pharma advisory board, outside the submitted work. The other authors have no conflicts of interest to declare. We thank Dr Kenneth S. Resnick for his participation in the survey.

The diagnosis of cutaneous and subcutaneous spindle cell neoplasms in children is often challenging and has potential therapeutic and prognostic implications. Although correctly diagnosing dermatofibrosarcoma protuberans and infantile fibrosarcoma is paramount, pathologists should not ignore a number of diagnostic pitfalls linked to mostly rare tumors with completely different clinical outcomes. In the last decade, a spectrum of novel entities has been described; information from molecular biology has helped to shape this new landscape for spindle cell tumors. Here, we review the most noteworthy neoplasms in this spectrum, with a focus on their histological similarities: fibroblastic connective tissue nevus, medallion-like dermal dendrocyte hamartoma, or plaque-like CD34-positive dermal fibroma, which share features with fibrous hamartoma of infancy; lipofibromatosis and lipofibromatosis-like neural tumor; and plexiform myofibroblastoma, a recently described neoplasm that should be distinguished from plexiform fibrohistiocytic tumor. These tumors also have genetic similarities, particularly gene rearrangements involving NTRK3 or NTRK1. These genetic features are not only essential for the differential diagnosis of infantile fibrosarcoma but are also of diagnostic value for lipofibromatosis-like neural tumors. The more recently described RET, RAF1, and BRAF gene fusions are also discussed.

ALK-positive histiocytosis is a rare subtype of histiocytic neoplasm first described in 2008 in 3 infants with multisystemic disease involving the liver and hematopoietic system. This entity has subsequently been documented in case reports and series to occupy a wider clinicopathologic spectrum with recurrent KIF5B-ALK fusions. The full clinicopathologic and molecular spectra of ALK-positive histiocytosis remain, however, poorly characterized. Here, we describe the largest study of ALK-positive histiocytosis to date, with detailed clinicopathologic data of 39 cases, including 37 cases with confirmed ALK rearrangements. The clinical spectrum comprised distinct clinical phenotypic groups: infants with multisystemic disease with liver and hematopoietic involvement, as originally described (Group 1A: 6/39), other patients with multisystemic disease (Group 1B: 10/39), and patients with single-system disease (Group 2: 23/39). Nineteen patients of the entire cohort (49%) had neurologic involvement (7 and 12 from Groups 1B and 2, respectively). Histology included classic xanthogranuloma features in almost one-third of cases, whereas the majority displayed a more densely cellular, monomorphic appearance without lipidized histiocytes but sometimes more spindled or epithelioid morphology. Neoplastic histiocytes were positive for macrophage markers and often conferred strong expression of phosphorylated extracellular signal-regulated kinase, confirming MAPK pathway activation. KIF5B-ALK fusions were detected in 27 patients, whereas CLTC-ALK, TPM3-ALK, TFG-ALK, EML4-ALK, and DCTN1-ALK fusions were identified in single cases. Robust and durable responses were observed in 11/11 patients treated with ALK inhibition, 10 with neurologic involvement. This study presents the existing clinicopathologic and molecular landscape of ALK-positive histiocytosis and provides guidance for the clinical management of this emerging histiocytic entity.

We read with interest Rusmini et al report1 that discussed the application of next-generation sequencing (NGS) in the diagnosis of systemic auto inflammatory diseases (SAID) in 2016. By developing an NGS panel of 10 SAID-associated genes on 50 patients with a known Sanger-identified variant, a third of them were found to carry one or more additional possible effective variants in at least one other gene. Nevertheless, their phenotypic contribution was doubtful, representing the most challenging issue for the use of NGS panels in the daily clinical practice. Herein, we report a striking illustration of the value of extended NGS in patients with unexpected phenotype. We describe the case of a child with prominent inflammatory and cutaneous phenotype, in whom the first NGS panel’s results hypothesised a diagnosis that is analogous to a chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature syndrome (CANDLE-like). Despite the identification of a single heterozygous variant in the PSMB8 gene, a second underlying pathogenic variant was suspected given that a genetic digenism is usually frequent in proteasome-associated auto-inflammatory syndromes. But there was more that met the eye: as the patient did not present typical features of CANDLE, genetic investigation was pursued with a whole-exome sequencing revealing a de novo frameshift mutation in the Sterile Alpha Motif Domain–containing protein 9-Like ( SAMD9L ) gene and leading to the diagnosis of SAMD9L-associated autoinflammatory disease (SAMD9L-SAAD). The girl was born to unrelated …

BACKGROUND:Multiple studies have compared the performance of artificial intelligence (AI)-based models for automated skin cancer classification to human experts, thus setting the cornerstone for a successful translation of AI-based tools into clinicopathological practice. OBJECTIVE:The objective of the study was to systematically analyse the current state of research on reader studies involving melanoma and to assess their potential clinical relevance by evaluating three main aspects: test set characteristics (holdout/out-of-distribution data set, composition), test setting (experimental/clinical, inclusion of metadata) and representativeness of participating clinicians. METHODS:PubMed, Medline and ScienceDirect were screened for peer-reviewed studies published between 2017 and 2021 and dealing with AI-based skin cancer classification involving melanoma. The search terms skin cancer classification, deep learning, convolutional neural network (CNN), melanoma (detection), digital biomarkers, histopathology and whole slide imaging were combined. Based on the search results, only studies that considered direct comparison of AI results with clinicians and had a diagnostic classification as their main objective were included. RESULTS:A total of 19 reader studies fulfilled the inclusion criteria. Of these, 11 CNN-based approaches addressed the classification of dermoscopic images; 6 concentrated on the classification of clinical images, whereas 2 dermatopathological studies utilised digitised histopathological whole slide images. CONCLUSIONS:All 19 included studies demonstrated superior or at least equivalent performance of CNN-based classifiers compared with clinicians. However, almost all studies were conducted in highly artificial settings based exclusively on single images of the suspicious lesions. Moreover, test sets mainly consisted of holdout images and did not represent the full range of patient populations and melanoma subtypes encountered in clinical practice.

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Autoinflammatory diseases result from the dysregulation of innate immune responses. Here, we show that (1) a mutation in the C-terminal region of the Cdc42 Rho guanosine triphosphatase (GTPase) leads to palmitoylation and is involved in a severe, complex immunohematoautoinflammatory phenotype and (2) a direct link between the Cdc42-mutated form and enhanced NF-κB signaling pathway is responsible for the patient’s inflammatory phenotype. The clinical and laboratory data of our patient (referred to as patient A.S.) are detailed in the Methods section in this article’s Online Repository at www.jacionline.org. The main clinical characteristics were severe neonatal dermatitis and flare-ups of a nonspecific urticarial, scaling rash. This rash worsened, with the formation of well-confined psoriasiform plaques and development of chronic psoriasiform erythroderma that was resistant to various lines of treatment (Fig 1, A and see Fig E1, A-D in this article’s Online Repository at www.jacionline.org). The patient also displayed acute episodes of hepatomegaly with cytolysis; mild facial dysmorphia; a permanent nonspecific inflammatory syndrome with occasional monocytosis; and in adulthood, mild hypereosinophilia and hyper-IgE that were putatively related to a skin barrier defect. There was no evidence of an autoimmune disease during childhood. No major infections or allergies were observed, but a chronic staphylococcal colonization that probably acts as a triggering factor for worsening skin inflammation was seen. Using whole exome sequencing, we identified a de novo c.556C>T (p.R186C) heterozygous mutation in cell division cycle 42 (CDC42) (Fig 1, B and see Fig E1, E and F). The mutation affects only the ubiquitously expressed Cdc42 form and not the brain form (see Fig E1, G and H). Cdc42 alternates between an inactive, cytosolic guanosine diphosphate–bound form and an active, membranous guanosine triphosphate–bound form; this cycle allows Cdc42 to interact with effectors and thus activate various biologic functions.1Rougerie P. Delon J. Rho GTPases: masters of T lymphocyte migration and activation.Immunol Lett. 2012; 142: 1-13Crossref PubMed Scopus (61) Google Scholar,2Cherfils J. Zeghouf M. Regulation of small GTPases by GEFs, GAPs, and GDIs.Physiol Rev. 2013; 93: 269-309Crossref PubMed Scopus (632) Google Scholar The cytosol/membrane cycle is regulated by guanosine diphosphate dissociation inhibitors (GDIs), which extract Cdc42 from endomembranes and plasma membranes and sequester it in the cytosol. Binding to membranes requires that Rho GTPases be lipidated by a geranyl-geranyl anchor attached to a cysteine residue in its C-terminal hypervariable region, C188 in Cdc42 (Fig 1, C). Whereas wild-type (WT) Cdc42 is distributed in the cytosol, nuclear envelope and in the Golgi apparatus to a small extent, we found that Cdc42 R186C is abnormally anchored in the Golgi apparatus (Fig 1, D and see Fig E2, A in this article’s Online Repository at www.jacionline.org). We studied whether the mutant Cdc42 influenced the WT protein’s localization. Quantification of the Pearson coefficient for the signals from WT Cdc42 versus for those from Cdc42 R186C showed that the 2 proteins localize independently of each other (see Fig E2, B). Furthermore, the Golgi localization of Cdc42 R186C is stable over time (see Fig E2, C). Using constitutively active and dominant-negative mutant forms of Cdc42, we showed that the localization defect is independent of Cdc42 activation state (see Fig E2, D). Lastly, the localization of Cdc42 R186C was specifically related to the cysteine at position 186, because substitution with a serine or leucine did not have much impact on localization of Cdc42 (see Fig E2, E-G). Curiously, the R186C mutation introduces a cysteine in a position that is palmitoylated in the related small GTPase H-Ras (see Fig E3, A in this article’s Online Repository at www.jacionline.org). In Cdc42 immunoprecipitation experiments, we demonstrated that Cdc42 R186C is palmitoylated (Fig 1, E). Interestingly, Cdc42 R186C no longer located to the Golgi when palmitoylation was pharmacologically blocked (Fig 1, F and see Fig E3, B-C). Thus, the cysteine 186 caused Cdc42 palmitoylation and leads to retention of the protein in the Golgi apparatus. We then hypothesized that this localization defect might modify the molecular partners with which Cdc42 could interact; we confirmed this hypothesis in mass spectrometry analyses. Interaction with GDI1 was significantly reduced by the R186C mutation (Fig 1, G). The crystal structure of the Cdc42/GDI1 complex shows that GDI1 interacts extensively with the lipidated hypervariable region and buries the geranyl-geranyl lipid inside a hydrophobic pocket.3Hoffman G.R. Nassar N. Cerione R.A. Structure of the Rho family GTP-binding protein Cdc42 in complex with the multifunctional regulator RhoGDI.Cell. 2000; 100: 345-356Abstract Full Text Full Text PDF PubMed Scopus (392) Google Scholar Importantly, the R186 residue is also buried inside the GDI1 (see Fig E4, A in this article’s Online Repository at www.jacionline.org). We therefore reasoned that the substitution of R186 by a palmitoylated cysteine would impair GDI1 binding. Biochemical experiments showed that Cdc42 R186C fails to interact with GDI1 (Fig 1, H). As a control for the lack of GDI1 interaction, we used another mutant described in other autoinflammatory patients, C188Y, which has been predicted to lack lipidation.4Gernez Y. de Jesus A.A. Alsaleem H. Macaubas C. Roy A. Lovell D. et al.Severe autoinflammation in 4 patients with C-terminal variants in cell division control protein 42 homolog (CDC42) successfully treated with IL-1β inhibition.J Allergy Clin Immunol. 2019; 144: 1122-1125Abstract Full Text Full Text PDF PubMed Scopus (37) Google Scholar We next investigated the functional consequences of the aberrant localization of Cdc42 R186C. Given that Cdc42 controls actin filament polymerization, we wondered whether actin polymerization would be affected. The cells of patient A.S. contained around 30% less F-actin than normal (Fig 2, A). Expression of Cdc42 R186C in starved CEM cells recapitulated the actin polymerization defect (Fig 2, B). In view of the patient’s systemic inflammatory phenotype, we found that his fibroblasts overproduced proinflammatory cytokines (Fig 2, C and see Fig E5 in this article’s Online Repository at www.jacionline.org) in an NF-κB-dependent manner (Fig 2, D). Accordingly, the patient’s cells displayed increases in p65 NF-κB phosphorylation and nuclear translocation (Fig 2, E and F). Moreover, Cdc42 R186C expression in control fibroblasts was sufficient to increase IL-8 and IL-1β production to levels similar to those measured in the patient’s cells (Fig 2, G). Remarkably, expression of Cdc42 R186C or C188Y induced NF-κB hyperactivation, whereas no activation was observed with these variants carrying a dominant negative mutation (Fig 2, H), indicating that these mutants must be activated by guanosine triphosphate to induce NF-κB signaling. Lastly, inhibition of palmitoylation reversed the NF-κB hyperactivation induced by Cdc42 R186C, indicating that the Golgi retention of Cdc42 is responsible for NF-κB overstimulation (Fig 2, I). Our results thus support a direct link between the Cdc42 R186C mutation and the cellular inflammatory phenotype and show that this is mediated by NF-κB. Our in-depth molecular characterization of the Cdc42 R186C mutant is in line with recent reports on other patients who had autoinflammatory syndromes and carried C-terminal variants of Cdc42.4Gernez Y. de Jesus A.A. Alsaleem H. Macaubas C. Roy A. Lovell D. et al.Severe autoinflammation in 4 patients with C-terminal variants in cell division control protein 42 homolog (CDC42) successfully treated with IL-1β inhibition.J Allergy Clin Immunol. 2019; 144: 1122-1125Abstract Full Text Full Text PDF PubMed Scopus (37) Google Scholar,5Lam M.T. Coppola S. Krumbach O.H.F. Prencipe G. Insalaco A. Cifaldi C. et al.A novel disorder involving dyshematopoiesis, inflammation, and HLH due to aberrant CDC42 function.J Exp Med. 2019; 216: 2778-2799Crossref PubMed Scopus (49) Google Scholar In our study, the doubly lipidated R186C Cdc42 mutant was retained in the Golgi (see Fig E4, B). This impaired its plasma membrane anchoring and resulted in actin polymerization defects and hyperactivation of NF-κB signaling. In conclusion, our study identifies a strong link between impaired cytosol/membrane cycling of Cdc42 resulting from abnormal double lipidation, partial defects in actin polymerization, and hyperactivation of NF-κB signaling, which can explain the pathophysiology of the disease. More broadly, our findings are consistent with reports in the literature that link inflammation with actin turnover6Pfajfer L. Mair N.K. Jimenez-Heredia R. Genel F. Gulez N. Ardeniz O. et al.Mutations affecting the actin regulator WD repeat-containing protein 1 lead to aberrant lymphoid immunity.J Allergy Clin Immunol. 2018; 142: 1589-1604.e11Abstract Full Text Full Text PDF PubMed Scopus (32) Google Scholar and membrane targeting of Rho GTPases.7Akula M.K. Shi M. Jiang Z. Foster C.E. Miao D. Li A.S. et al.Control of the innate immune response by the mevalonate pathway.Nat Immunol. 2016; 17: 922-929Crossref PubMed Scopus (103) Google Scholar, 8Park Y.H. Wood G. Kastner D.L. Chae J.J. Pyrin inflammasome activation and RhoA signaling in the autoinflammatory diseases FMF and HIDS.Nat Immunol. 2016; 17: 914-921Crossref PubMed Scopus (236) Google Scholar, 9Akula M.K. Ibrahim M.X. Ivarsson E.G. Khan O.M. Kumar I.T. Erlandsson M. et al.Protein prenylation restrains innate immunity by inhibiting Rac1 effector interactions.Nat Commun. 2019; : 3975Crossref PubMed Scopus (19) Google Scholar Thus, further investigation of the various consequences of CDC42 mutations are required because these mutations arise in a broad spectrum of clinical phenotypes. Ultimately, it offers the possibility of designing specific therapeutic targeting of this pathway that is newly involved in autoinflammatory diseases. We thank patient A.S. and his family for participating in this research. Patient A.S. was born at term to healthy, nonconsanguineous, white parents. His biological father was confirmed by a paternity test. From his first few days of life onward, patient A.S. displayed episodes of fever, hepatosplenomegaly, pancytopenia, and a diffuse maculopapular rash with frequent relapses and a progressive worsening of his general condition. When he was 2 months of age, an acute episode of pancytopenia prompted a clinical investigation. This investigation revealed extramedullary hematopoiesis (in a needle liver biopsy specimen), nonspecific lymphoid hyperplasia (in a lymph node biopsy specimen), and a relatively acellular bone marrow. The skin biopsy specimen showed a moderately intense, nonspecific inflammatory infiltrate. Although systemic treatment with high-dose steroids led to some improvement, the patient became corticoid dependent. At the age of 11 months, A.S. displayed relapses of more strongly inflammatory, scaly, erythematous skin lesions and fluctuating hepatosplenomegaly with cytolysis. These conditions had a severe impact on growth (–4 SDs). At the age of 16 months, the patient's health worsened, with a moderate bone marrow fibrosis, persistent skin flare-ups, and episodes of fever and cytolysis with a nonspecific inflammatory syndrome. There were no signs of infection or autoimmune disease. Splenectomy performed when the patient was 23 months old showed extramedullary hematopoiesis and no evidence of neoplastic disease. Allogeneic bone marrow transplantation was performed when the patient was 24 months old; immune reconstitution was good, with 100% donor chimerism. However, scaly cutaneous lesions with a psoriasiform aspect appeared just 6 days after the transplant, despite the absence of any signs of graft-versus-host disease. We did not observe vacuolization or necrosis of basal layer keratinocytes or lymphocytic exocytosis (ie, satellite cell necrosis) on multiple sections. The skin lesions worsened gradually; 8 months after the transplantation, the patient's whole body was affected by erythroderma. On a skin biopsy specimen, sterile pustular psoriasis-type lesions were noted (Fig 1, A). The fever and pancytopenia disappeared totally, whereas hepatomegaly and liver cytolysis persisted. The patient is now a 23-year-old adult with permanent, severe, psoriasiform erythroderma; flares of more pronounced, painful skin inflammation (Fig 1, A and Fig E1, A-D); chronic Staphylococcus aureus skin infections; and recurrent episodes of liver cytolysis. Viral infections and the staphylococcal skin infections worsen the organ inflammation. Clinically, we have observed aortic insufficiency, mild facial dysmorphy, acquired hypophosphatemic rickets, growth retardation, a nonspecific inflammatory syndrome, monocytosis of varying intensity (>1000/mm3), hypereosinophilia (>600/mm3), and hyper-IgE (>700 IU/mL). The patient’s clinical characteristics (flares of inflammation in different organs, episodes of fever, and a nonspecific inflammatory syndrome) are suggestive of an autoinflammatory disease. After transient improvements, the patient has failed to respond to treatments with various immunosuppressants and/or biologics (including anti–IL-1 receptor and anti–TNF-α, which have been tested in severe and pustular psoriasis) (Fig E1). The pEGFP-C3 vector was from Clontech (Mountain View, Calif). The pEGFP-C3-Cdc42 plasmid was provided by L.I. Salazar-Fontana.E1Salazar-Fontana L.I. Barr V. Samelson L.E. Bierer B.E. CD28 engagement promotes actin polymerization through the activation of the small Rho GTPase Cdc42 in human T cells.J Immunol. 2003; 171: 2225-2232Crossref PubMed Scopus (65) Google Scholar Constitutively active L61Q and dominant negative T17N mutants that mimic the guanosine triphosphate– and guanosine diphosphate–bound forms of Cdc42 respectively, were previously described.E2Faure S. Salazar-Fontana L.I. Semichon M. Tybulewicz V.L. Bismuth G. Trautmann A. et al.ERM proteins regulate cytoskeleton relaxation promoting T cell-APC conjugation.Nat Immunol. 2004; 5: 272-279Crossref PubMed Scopus (209) Google Scholar The pRK5-myc-Cdc42 plasmids were all obtained from Addgene. The Cdc42 mutants (R186C, R186S, R186L or C188Y) were generated by site-directed mutagenesis (Quickchange kit, Agilent Technologies, Les Ulis, France). WT and R186C Cdc42 were also subcloned in the pLenti-III-CMV vector from Applied Biological Materials Inc (Richmond, British Columbia, Canada). The lymphoblastoid T-cell line CEM was grown in RPMI 1640 medium plus Glutamax medium (Gibco, Illkirch, France) supplemented with 10% heat-inactivated FCS, antibiotics (50 U/mL of penicillin and 50 μg/mL of streptomycin [Gibco]), 10 mM sodium pyruvate (Gibco), and 10 mM HEPES (Gibco). Primary human peripheral blood T cells (PBTs) were purified from the blood of healthy donors (provided by Etablissement Français du Sang) by using a Ficoll gradient separation before negative selection with a cocktail of antibodies (EasySep Human T cell isolation kit [Stem Cell Technologies, Grenoble, France]) according to the manufacturer’s recommendation. PBTs were grown in complete RPMI 1640 medium supplemented by 10% human AB serum. Primary human fibroblasts from the patient and healthy donors were obtained from skin biopsy specimens. Human bone marrow endothelial cell (HBMEC), HEK 293T, RPE1 cell lines and primary human fibroblasts were cultivated in complete Dulbecco modified Eagle medium (Gibco). CEM cells (2 ×106) were centrifuged for 5 minutes at 1200 rpm and washed once in PBS (Gibco). The cells were then transfected by nucleofection with 5 μg of DNA in 100 μL of Cell Line Nucleofector Solution V (Lonza, Levallois-Perret, France) by using the C-016 program (Amaxa Biosystems). After transfection, 500 μL of complete RPMI medium was added to the cells, which were then deposited in 6-well plates containing 2 mL of medium. The plate was incubated overnight. The transfection of the HBMEC cells was carried out according to the same protocol but with 3 μg of DNA for 0.5 × 106 cells in 100 μL of Cell Line Nucleofector Solution V (Lonza) with the program U-015. For the cotransfection experiments, 0.5 × 106 HBMEC cells were transfected with 2.5 μg of each of the plasmids of interest encoding for GFP-Cdc42 R186C together with either Myc-Cdc42 WT or an empty vector. The PBTs were transfected with 5 μg of DNA for 5 × 106 cells in 100 μL of Human T-Cell Nucleofector Solution (Lonza) with the program U-014 (Amaxa Biosystems). The HEK cells were transfected with plasmids encoding green fluorescent protein (GFP)-tagged Cdc42 variants by using calcium phosphate transfection or a Lipofectamine LTX Kit (Life Technologies, Carlsbad, Calif). The RPE1 cells were transfected by using Fugene (Promega, Madison, Wis). Lentiviral production and fibroblasts infection were performed as described.E3Bal E. Park H.S. Belaid-Choucair Z. Kayserili H. Naville M. Madrange M. et al.Mutations in ACTRT1 and its enhancer RNA elements lead to aberrant activation of Hedgehog signaling in inherited and sporadic basal cell carcinomas.Nat Med. 2017; 23: 1226-1233Crossref PubMed Scopus (36) Google Scholar To detect palmitoylation, the RPE1 cells that had been transfected 48 hours earlier with different Myc-tagged constructs were starved for 1 hour at 37°C in IM (Glasgow minimal essential medium buffered with 10 mM HEPES [pH 7.4]) and incubated for 2 hours at 37°C in IM with 200 μCi/mL of 3H-palmitic acid (9,10-3H(N)) (American Radiolabeled Chemicals, Inc, St Louis, Mo). The cells were washed, incubated in complete Dulbecco modified Eagle medium for 10 minutes, washed 3 times with cold PBS at 4°C, directly lysed for 30 minutes at 4°C in lysis buffer (0.5 % Nonidet P-40, 500 mM Tris [pH 7.4], 20 mM EDTA, 10 mM NaF, 2 mM benzamidine, and protease inhibitor cocktail [Roche, Basel, Switzerland]), and centrifuged for 3 minutes at 5000 rpm. Supernatants were subjected to preclearing with G Sepharose beads before being subjected to immunoprecipitation reaction that included overnight incubation with anti-Myc affinity gel (Thermo Scientific, Waltham, Mass). After immunoprecipitation, the washed beads were incubated for 5 minutes at 90°C in reducing sample buffer before 4% to 20% gradient SDS-PAGE and revelation with a mouse anti-Myc 9E10 antibody (Covance, Princeton, NJ). After SDS-PAGE, the gel was incubated in a fixative solution (25% isopropanol, 65% H2O, and 10% acetic acid), followed by a 30-minute incubation with signal enhancer Amplify NAMP100 (GE Healthcare, Chicago, Ill). The radiolabeled products were revealed by using Typhoon phosphoimager. For GDI1 coimmunoprecipitation assay, the HEK cells were lysed by using 50 mM TRIS base, Triton 2%, and 200 mM NaCl, as well as 1 tablet/10 mL of the protease inhibitor Mini-complete, EDTA-free (Roche). After removal of insoluble fragments via centrifugation at 12,000 g for 25 min, the lysates were incubated with 15 μL of GFP-Trap Agarose beads from Chromotek (Planegg, Germany) for 1 hour at 4°C on a rotary wheel. The beads were then washed 3 times for 10 minutes with wash buffer (250 mM NaCl and 0.1 % Triton in PBS) followed by detection of GDI1 interaction with GFP-tagged Cdc42 variants by using Western blot. The primary antibodies used were anti–GFP–horseradish peroxidase (Novus Biologicals, Centennial, Colo) and anti–Rho GDIα (Santa Cruz Biotechnology, Santa Cruz, Calif). All biochemistry experiments are representative of at least 3 independent experiments. GFP immunoprecipitation assays were carried out as described earlier with 1 exception; namely, a special wash buffer was used to wash the Chromotek beads after the binding assays. The mass spectrometry wash buffer was prepared by using 50 mM TRIS base, 150 mM NaCl, 1 mM EDTA, and 2.5 mM MgCl2 (pH adjusted to 7.5). Following the final wash, the beads were stored with wash buffer at 4°C before deposition at the Institut Curie Mass Spectrometry and Proteomics facility (LSMP). The proteins on the beads were washed twice with 100 μL of 25 mM NH4HCO3, after which we performed on-bead digestion with 0.2 μg of Trypsin/LysC (Promega) for 1 hour in 100 μL of 25 mM NH4HCO3. The samples were then loaded onto homemade C18 StageTips for desalting. Peptides were eluted by using 40:60 MeCN/H2O plus 0.1% formic acid and vacuum-concentrated to dryness. Online chromatography was performed with an RSLCnano system (Ultimate 3000, Thermo Scientific) coupled to an Orbitrap Fusion Tribrid mass spectrometer (Thermo Scientific). Peptides were trapped on a C18 column (75-μm inner diameter × 2 cm; nanoViper Acclaim PepMapTM 100, Thermo Scientific) with buffer A (2/98 MeCN/H2O in 0.1% formic acid) at a flow rate of 4 μL/min over 4 minutes. Separation was performed on a 50 cm × 75-μm C18 column (nanoViper Acclaim PepMapTM RSLC, 2 μm, 100 Å, Thermo Scientific) regulated to a temperature of 55°C with a linear gradient of 5% to 25% buffer B (100% MeCN in 0.1% formic acid) at a flow rate of 300 nL/min over 100 minutes. Full-scan MS was performed by using the Orbitrap analyzer with a resolution set to 120,000, and ions from each full scan were high-density collisional dissociation–fragmented and analyzed in the linear ion trap. For identification, the data were searched against the Homo sapiens (UP000005640) SwissProt database by using Sequest HF through proteome discoverer (version 2.2). Enzyme specificity was set to trypsin, and a maximum of 2 missed cleavage sites were allowed. Oxidized methionine, N-terminal acetylation, and carbamidomethyl cysteine were set as variable modifications. The maximum allowed mass deviation was set to 10 ppm for monoisotopic precursor ions and 0.6 Da for MS/MS peaks. The resulting files were further processed by using myProMS E4 v3.6 (work in progress). The false discovery rate calculation was performed by using Percolator and was set to 1 % at the peptide level for the whole study. The label-free quantification was performed by peptide extracted ion chromatograms (XICs) computed with MassChroQ version 2.2.E5Valot B. Langella O. Nano E. Zivy M. MassChroQ: a versatile tool for mass spectrometry quantification.Proteomics. 2011; 11: 3572-3577Crossref PubMed Scopus (140) Google Scholar For protein quantification, XICs from proteotypic peptides shared between compared conditions (TopN matching) with no missed cleavages were used. Median and scale normalization was applied on the total signal to correct the XICs for each biologic replicate. To estimate the significance of the change in protein abundance, a linear model (adjusted on peptides and biologic replicates) was performed and P values were adjusted with a Benjamini-Hochberg false discovery rate procedure with a control threshold set to 0.05. The mass spectrometry proteomics data have been deposited with the ProteomeXchange Consortium via the PRIDEE6Vizcaino J.A. Csordas A. Del-Toro N. Dianes J.A. Griss J. Lavidas I. et al.2016 update of the PRIDE database and its related tools.Nucleic Acids Res. 2016; 44: 11033Crossref PubMed Scopus (19) Google Scholar partner repository, with the data set identifier PXD016251 (username, [email protected] ; password, MrXYoj4j). For each indicated partner (blue dots), the number of identified peptides that bind to mutant Cdc42 R186C is shown as a function of the number of peptides binding to WT Cdc42. Partners that fall on the black line bind WT and mutant Cdc42 equally well. CEM and HBMEC cells were incubated overnight in complete culture medium containing 30 μM 2-bromo-palmitate (Sigma, St Louis, Mo). Cells were stimulated with FSL-1 (a TLR2/6 agonist [1 μg/mL]), LTA (a TLR2 agonist [10 μg/mL]), LPS (a TLR4 agonist [1 μg/mL]), TNF-α (20 ng/mL), and IL-1β (20 ng/mL) for 24 hours. Total RNA was extracted from patient and healthy control fibroblasts stimulated or left unstimulated with a Qiagen (Hilden, Germany) RNA mini kit according to the manufacturer’s instructions. cDNA was synthesized thanks to ready-to-use iScript cDNA supermix (BioRad, Hercules, Calif). Real-time quantitative PCR was performed with Syber Green PCR master mix (Life Technologies) according to the manufacturer’s instructions. The results were read with the CFX384 Real Time System machine. Relative expression of mRNA was determined by the 2-ΔΔC(t) method by using GAPDH and ACTIN as housekeeping genes. Supernatants were collected, and ELISA (InvivoGen, San Diego, Calif) for different cytokines was performed according to the manufacturer’s instructions. Absorbance results were read with the Infinite f200 pro TECAN machine. HEK 293T cells were transfected with NF-κB–dependent firefly luciferase vector (Ig-κLUC), Renilla luciferase vector as an internal control, and different constructions of Cdc42 following the manufacturer’s indications. The cells were lysed in passive lysis buffer, and luciferase activity was read in the Infinite f200 pro TECAN machine. After cells were washed with PBS, they were fixed with 4% paraformaldehyde (Electron Microscopy Sciences, Hatfield, Pa) for 10 minutes. They were then washed once in PBS containing 1 % BSA (Sigma) and twice in a permeabilization buffer (PBS containing 0.1% saponin [Fluka Biochemika, Illkirch, France] and 0.2% BSA). The cells were incubated for 45 minutes with the following primary antibodies: anti-GM130 (Santa Cruz Biotechnology), anti-p65 NF-κB (Santa Cruz Biotechnology), or an anti-myc tag Alexa Fluor 488 antibody (Cell Signaling Technology, Danvers, Mass; 9B11). After they were washed in the permeabilization buffer, the cells were incubated for 30 minutes with secondary anti-goat or anti-mouse antibodies conjugated to Alexa Fluor 568 (Invitrogen, Carlsbad, Calif). After an additional wash, the cells were incubated with Hoechst (Sigma) for 5 minutes to stain nuclei in blue. For the cotransfection experiments, the cells were stained according to the same protocol except for the myc staining that was performed by using an unconjugated anti-myc tag antibody (Santa Cruz Biotechnology, 9E10) followed by an AMCA anti-mouse antibody (Jackson ImmunoResearch, Ely, United Kingdom). The images were acquired by using a Nikon TE300 fluorescence microscope, a Cascade Photometrics camera, and Metamorph version 7.8.9.0 software. Three oil immersion objectives were used: 40×, 60×, and 100×. Z-stack images were generated, and then (after deconvolution and projection) the Pearson coefficient (PC) was measured on Fiji (ImageJ software, version 1.51u) by using a macro containing the Coloc2 plugin. This coefficient measures the degree of overlap between 2 stainings and was used to quantify the degree of colocalization between Cdc42 and the Golgi apparatus. A PC value of 0 means that there is no colocalization between the 2 stainings. By contrast, a PC value of 1 means that there is a perfect colocalization between Cdc42 and the Golgi. All immunocytochemistry experiments and quantifications shown are representative of at least 3 independent experiments. The degree of p65 NF-κB nuclear translocation was quantified on Fiji from randomly acquired images by measuring the mean fluorescence intensity of the staining in the nucleus divided by the mean fluorescence intensity in the cytosol with use of the same size regions. A ratio higher than 1 was considered to be the hallmark of a cell presenting p65 NF-κB nuclear translocation. The transfected CEM cells were used directly or serum-starved during the indicated times in RPMI medium alone. The cells were then fixed and permeabilized as previously explained. Actin filaments were stained with 0.5 U/mL of phalloidin Alexa Fluor 647 (Invitrogen). The amount of filamentous actin (F-actin) present in the CEM cells was measured by flow cytometry (FACSCalibur, BD Biosciences, Le Pont de Claix, France) and analyzed with Flowjo version 7 software. Alexa Fluor 488 Mouse Anti NF-κB p65 (pS529) from BD Biosciences was used on fibroblasts. Statistical analyses were carried out by using GraphPad Prism 5 software (GraphPad Software Inc, La Jolla, Calif). The results represent the means plus or minus SEs of at least 3 independent experiments. The levels of significance were calculated by ANOVA or the Student t test: ∗P < .05; ∗∗P < .01; ∗∗∗P < .001, ∗∗∗∗P < .0001.

To the Editor: Cutaneous involvement by acute lymphoblastic leukemia/lymphoblastic lymphoma (ALL/LBL) is very uncommon. Current knowledge of this situation remains limited, based on small retrospective case series without data regarding overall survival (OS) and associated prognostic factors nor molecular features.1Millot F. Robert A. Bertrand Y. et al.Cutaneous involvement in children with acute lymphoblastic leukemia or lymphoblastic lymphoma.Pediatrics. 1997; 100: 60-64Crossref PubMed Scopus (82) Google Scholar, 2Lee W.J. Moon H.R. Won C.H. et al.Precursor B-or T-lymphoblastic lymphoma presenting with cutaneous involvement: a series of 13 cases including 7 cases of cutaneous T-lymphoblastic lymphoma.J Am Acad Dermatol. 2014; 70: 318-325Abstract Full Text Full Text PDF PubMed Scopus (33) Google Scholar, 3Boccara O. Laloum-Grynberg E. Jeudy G. et al.Cutaneous B-cell lymphoblastic lymphoma in children: a rare diagnosis.J Am Acad Dermatol. 2012; 66: 51-57Abstract Full Text Full Text PDF PubMed Scopus (24) Google Scholar Besides, no data about differential antigen expression of tumoral cells in skin vs bone marrow are available. Our objective was to describe outcome, prognostic factors, and clinicophenotyping specificities of ALL/LBL with skin involvement. We collected retrospective data from a multicenter cohort of patients with ALL/LBL with cutaneous involvement from 13 hospitals from 1997 to 2018. Patients’ characteristics are listed in Table I. Among 38 patients with ALL/LBL (12 females, 26 males), 17 were B-ALL/LBL and 21 were T-ALL/LBL. Median age at diagnosis was 22 years (range, 0-94 years). Complete follow-up was available for 27 patients, and median follow-up was 36 months (range, 1-130 months). The 5-year OS was 56% (95% confidence interval, 39%-79%). On univariate analysis for OS, an association for reduced OS was found for adulthood (hazard ratio, 11; 95% confidence interval, 1.5-88; P = .02) and relapse (hazard ratio, 19; 95% confidence interval, 2.3-159; P = .006) during follow-up, whereas all patients with isolated skin lesions were alive at the end of follow-up regardless of phenotype or molecular risk stratification (Fig 1).4Moorman A.V. Enshaei A. Schwab C. et al.A novel integrated cytogenetic and genomic classification refines risk stratification in pediatric acute lymphoblastic leukemia.Blood. 2014; 124: 1434-1444Crossref PubMed Scopus (142) Google ScholarTable IClinical, follow-up, and pathologic features of the cohortVariables∗Categorical data are presented as number (%) and continuous data as indicated.All patientsB-ALL/LBLT-ALL/LBLPClinical data Sex381721.307Female12 (32)7 (41)5 (24)Male26 (68)10 (59)16 (76) Age at diagnosis381721.018Median (range), y22 (0-94)8 (0-72)32 (1-94)Child (<18 y)14 (37)10 (59)4 (19)Adult24 (63)7 (41)17 (81) Onset of skin lesions361719.168Before hematologic diagnosis11 (31)6 (35)5 (26)At the hematologic diagnosis13 (36)4 (24)9 (48)After hematologic diagnosis8 (22)3 (18)5 (26)No hematologic involvement4 (11)4 (23)0 (0) Number of skin lesions381721<.001Single13 (34)11 (65)2 (10)Multiple25 (66)6 (35)19 (90) Type of skin lesions381721.483Nodule/tumor32 (84)15 (88)17 (81)Macule/patch6 (16)1 (6)5 (24)Other4 (11)1 (6)3 (14) Topography of skin lesions371720.743Head and neck20 (54)10 (59)10 (50)Other17 (46)7 (41)10 (50) Extension of ALL/LBL341618.005Lymphoma9 (26)1 (6)8 (44)Leukemia21 (62)11 (69)10 (56)Skin lesions only4 (12)4 (25)0 (0)Follow-up data Follow-up, mean (range), mo36 (1-130)38,5 (6-130)25 (1-123) First-line treatment2913†Including all patients cases with skin lesions only.16Radiotherapy000Standard induction polychemotherapy29 (100)13 (45)16 (55) Complete remission during follow-up271314>.99Yes24 (88)12 (92)12 (86)No3 (12)1 (8)2 (14) Relapse271314>.99Yes12 (44)6 (46)6 (43)No15 (56)7 (54)8 (57) Status at the end of the follow-up301416.483Alive17 (57)9 (64)8 (50)Dead13 (43)5 (36)8 (50)Pathologic data Cell size321517.418Small/medium (n = 3)7 (22)3 (20)4 (24)Medium (n = 13)16 (50)6 (40)10 (59)Medium/large (n = 4)9 (28)6 (40)3 (17) Localization of the infiltrate341519>.99Dermis25 (74)11 (73)14 (74)Dermis/Hypodermis9 (26)4 (27)5 (26)Immunohistochemical markers CD20327+/150+/17 CD79a2015+/160+/4 CD3290+/1017+/19 CD2120+/18+/11 CD5201+/710+/13 CD7131+/29+/11 CD1a140+/24+/12 CD103116+/168+/15 TDT3014+/1613+/14 CD34217+/113+/10 CD99114+/74+/4Ki67, median (range), %90 (40-100)90 (70-100)90 (40-100)ALL, Acute lymphoblastic leukemia; LBL, lymphoblastic lymphoma; No., number.∗ Categorical data are presented as number (%) and continuous data as indicated.† Including all patients cases with skin lesions only. Open table in a new tab ALL, Acute lymphoblastic leukemia; LBL, lymphoblastic lymphoma; No., number. The analysis of differential antigen expression in skin vs bone marrow was performed in 9 patients and showed only 1 adult man with T-ALL with unequivocal discordant expression (Supplemental Table I, available via Mendeley, https://doi.org/10.17632/5b38d3v62c.2). Terminal deoxynucleotidyl transferase was negative in bone marrow flow cytometric analysis and positive in cutaneous immunohistochemical staining. Also, 2 patients with B-ALL with minimal discordant antigen expression in skin were interpreted as very weak positivity in immunohistochemistry, suggesting that thresholds to consider positivity may differ according to the technique and may explain the discrepancy. Clinically, a solitary skin lesion was found in 65% of patients with B-ALL/LBL whereas 90% of patients with T-ALL/LBL had multiple skin lesions (P < .001) (Supplemental Figs 1 and 2, available via Mendeley https://doi.org/10.17632/5b38d3v62c.2). In 31% of patients, the skin lesions appeared before the hematologic diagnosis (median, 2.5 months). It is worth noting that 4 patients had skin lesions only, without extracutaneous involvement, and were mostly children with B-LBL. Cytogenetic and oncogenetic analyzes showed known ALL/LBL alterations without specific pattern (Supplemental Table II, available via Mendeley, https://doi.org/10.17632/5b38d3v62c.2). Cutaneous involvement by ALL/LBL does not seem to portend a poor prognosis by itself. Only adulthood and relapse during follow-up up were associated with reduced OS. We emphasized that phenotypic changes of leukemic cells in skin compared with those in bone marrow seem to be rare events in ALL/LBL with cutaneous involvement, unlike what is known in acute myeloid leukemia.5Cronin D.M.P. George T.I. Sundram U.N. An updated approach to the diagnosis of myeloid leukemia cutis.Am J Clin Pathol. 2009; 132: 101-110Crossref PubMed Scopus (74) Google Scholar Clinically, skin lesions can reveal the hematologic disease, and considerations regarding their aspects should be made for diagnosis, especially for solitary scalp masses in pediatric patients. This series is limited by the extended period of inclusion, implying heterogeneous treatments that might affect outcome findings. However, our cohort is, to our knowledge, the largest case series reported so far, providing new insights on ALL/LBL with skin involvement. Further studies are needed to fully understand and improve the management of this rare disease.

Intramuscular capillary-type hemangioma now called intramuscular hemangioma (IMH) has been defined recently and is classified in the category of “provisionally unclassified vascular anomalies,” according to the latest revision of the International Society for the Study of Vascular Anomalies classification.1 Several reported cases of IMH have been misdiagnosed and confused with common intramuscular venous malformations.2 Here we report the case of a 3-year-old child who had an IMH presenting as a rapidly growing mass.

Pediatric DermatologyVolume 37, Issue 1 p. 204-206 PHOTOQUIZ Cutis marmorata telangiectatica congenita-like lesion with fibrotic appearance Nicole Knöpfel MD, Corresponding Author Nicole Knöpfel MD nicole.knoepfel@kispi.uzh.ch orcid.org/0000-0002-6438-6550 Department of Pediatric Dermatology, University Children's Hospital Zurich, Zurich, Switzerland Correspondence Nicole Knöpfel, MD, Department of Pediatric Dermatology, University Children’s Hospital Zurich, Steinwiesstrasse 75, CH-8032 Zürich, Switzerland Email: nicole.knoepfel@kispi.uzh.chSearch for more papers by this authorCarina M. Butzmann MD, Carina M. Butzmann MD Department of Pediatric Dermatology, University Children's Hospital Zurich, Zurich, SwitzerlandSearch for more papers by this authorAline Büchner MD, Aline Büchner MD Department of Pediatric Dermatology, University Children's Hospital Zurich, Zurich, SwitzerlandSearch for more papers by this authorMartin Theiler MD, Martin Theiler MD orcid.org/0000-0001-7160-3958 Department of Pediatric Dermatology, University Children's Hospital Zurich, Zurich, Switzerland Department of Dermatology, University Hospital Zurich, Zurich, SwitzerlandSearch for more papers by this authorSylvie Fraitag MD, Sylvie Fraitag MD Department of Pathology, Institut Imagine, APHP, Hôpital Universitaire Necker-Enfants Malades, Université Paris Descartes - Sorbonne Paris Cité, Paris, FranceSearch for more papers by this authorLisa Weibel MD, Lisa Weibel MD Department of Pediatric Dermatology, University Children's Hospital Zurich, Zurich, Switzerland Department of Dermatology, University Hospital Zurich, Zurich, SwitzerlandSearch for more papers by this author Nicole Knöpfel MD, Corresponding Author Nicole Knöpfel MD nicole.knoepfel@kispi.uzh.ch orcid.org/0000-0002-6438-6550 Department of Pediatric Dermatology, University Children's Hospital Zurich, Zurich, Switzerland Correspondence Nicole Knöpfel, MD, Department of Pediatric Dermatology, University Children’s Hospital Zurich, Steinwiesstrasse 75, CH-8032 Zürich, Switzerland Email: nicole.knoepfel@kispi.uzh.chSearch for more papers by this authorCarina M. Butzmann MD, Carina M. Butzmann MD Department of Pediatric Dermatology, University Children's Hospital Zurich, Zurich, SwitzerlandSearch for more papers by this authorAline Büchner MD, Aline Büchner MD Department of Pediatric Dermatology, University Children's Hospital Zurich, Zurich, SwitzerlandSearch for more papers by this authorMartin Theiler MD, Martin Theiler MD orcid.org/0000-0001-7160-3958 Department of Pediatric Dermatology, University Children's Hospital Zurich, Zurich, Switzerland Department of Dermatology, University Hospital Zurich, Zurich, SwitzerlandSearch for more papers by this authorSylvie Fraitag MD, Sylvie Fraitag MD Department of Pathology, Institut Imagine, APHP, Hôpital Universitaire Necker-Enfants Malades, Université Paris Descartes - Sorbonne Paris Cité, Paris, FranceSearch for more papers by this authorLisa Weibel MD, Lisa Weibel MD Department of Pediatric Dermatology, University Children's Hospital Zurich, Zurich, Switzerland Department of Dermatology, University Hospital Zurich, Zurich, SwitzerlandSearch for more papers by this author First published: 29 January 2020 https://doi.org/10.1111/pde.13958Citations: 1 Knöpfel and Butzmann contributed equally and shared first authorship. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume37, Issue1January/February 2020Pages 204-206 RelatedInformation

To the Editor: Adenosine deaminase 2 deficiency (DADA2) is a monogenic autoinflammatory disease associated with ADA2 mutations.1Zhou Q. Yang D. Ombrello A.K. et al.Early-onset stroke and vasculopathy associated with mutations in ADA2.N Engl J Med. 2014; 370: 911-920Crossref PubMed Scopus (391) Google Scholar Diagnosis of DADA2 remains difficult given its variable clinical presentation.2Rama M. Duflos C. Melki I. et al.A decision tree for the genetic diagnosis of deficiency of adenosine deaminase 2 (DADA2): a French reference centres experience.Eur J Hum Genet. 2018; 26: 960-971Crossref PubMed Scopus (36) Google Scholar Although no tests are commercially available, serum ADA2 activity measurement can help secure the diagnosis, which is confirmed by ADA2 sequencing. Recently, Rama et al2Rama M. Duflos C. Melki I. et al.A decision tree for the genetic diagnosis of deficiency of adenosine deaminase 2 (DADA2): a French reference centres experience.Eur J Hum Genet. 2018; 26: 960-971Crossref PubMed Scopus (36) Google Scholar proposed a decision tree for the genetic diagnosis of DADA2 based on prerequisites including, among others, cutaneous manifestations. However, to our knowledge, no study has specifically described DADA2's dermatologic spectrum. Furthermore, pathologic findings on skin biopsy samples have rarely been reported,1Zhou Q. Yang D. Ombrello A.K. et al.Early-onset stroke and vasculopathy associated with mutations in ADA2.N Engl J Med. 2014; 370: 911-920Crossref PubMed Scopus (391) Google Scholar,3Gonzalez Santiago T.M. Zavialov A. Saarela J. et al.Dermatologic features of ADA2 deficiency in cutaneous polyarteritis nodosa.JAMA Dermatol. 2015; 151: 1230-1234Crossref PubMed Scopus (50) Google Scholar and specific histologic features remain to be determined. We conducted a multicenter, retrospective study with assessment of clinical and pathologic dermatologic findings among 8 French patients with DADA2. Cutaneous polyarteritis nodosa (cPAN) was defined as fibrinoid necrotizing vasculitis affecting the small arteries and arterioles (≥300 μm) in the panniculus and dermal-subcutaneous junction as described by Ishibashi and Chen4Ishibashi M. Chen K.-R. A morphological study of evolution of cutaneous polyarteritis nodosa.Am J Dermatopathol. 2008; 30: 319-326Crossref PubMed Scopus (39) Google Scholar in a 4-stage process with exclusion after clinicopathologic correlation of differential diagnoses, particularly antineutrophil cytoplasmic antibody–associated vasculitis. DADA2's main clinical features are presented in Table I and detailed in Supplemental Table I (available at Mendeley via https://data.mendeley.com/datasets/xd9mp9tn3x/draft?a=a2c80a86-9920-4422-b2a2-16d9e5aca560). Median age at first symptom was 9.5 years (range, 0.5-29 years), whereas median age at diagnosis was 25.5 years (range, 6-38 years.Table IMain clinical and pathologic skin features of the 8 French patients with DADA2Patient/number of biopsiesSkin manifestationsExtracutaneous manifestationsSite of biopsyThrombosisType of vesselsVasculitis∗Definitions of the cPAN stages by Ishibashi and Chen4 are as follows. Acute: endothelial loss and fibrin thrombi with neutrophil infiltration without obvious internal elastic lamina disruption and medial fibrinoid necrosis. Subacute: mixed-cell infiltrates showing a unique intimal target-like fibrinoid necrosis with fibrinoid leakage extending through the disrupted sites of the internal elastic lamina to the media. Reparative: intimal fibroblastic proliferation and perivascular neovascularization with predominant infiltrates of histiocytes and lymphocytes. Healed: minimal cellular inflammation with occlusive intimal thickening. Thrombosis was defined as complete occlusion of the vascular lumen by a cluster of fibrin.Type of vesselsOther findings1/1Livedo racemosaPerimalleolar ulcersRaynaud phenomenonAtrophie blancheRecurrent fever, increased CRP level, abdominal pain, peripheral neuropathyLeg ulcerNo—No—Pyogenic granuloma2/1Livedo racemosaRecurrent fever, arthralgia, myalgia, hepatitisLivedo on the legNo—No—Slight perivenular lymphocytic infiltrate in hypodermis3/13/23/33/43/5Livedo racemosaLeg nodulesPerimalleolar ulcersAtrophie blancheAnemia, increased CRP levelNodule on the legLivedo on an ankleLivedo on the trunkNodule on an ankleNodule on the legYesYesNoYesYesHypodermal capillariesDermal capillaries—Dermal and hypodermal capillariesDermal and hypodermal capillariesNoNoNoNoNo—————Nonspecific inflammation4/1Livedo racemosaLeg nodulesDigital necrosisRaynaud phenomenonErythematous feet papulesRecurrent fever, recurrent ENT infections, cerebral infarct, hypogammaglobulinemiaLivedo on the thigh (infiltrated zone)YesDermal and hypodermal capillariesSubacute cPANDeep dermis medium-sized artery—5/1Livedo racemosaUlcerated leg nodulesLeg nodulesPsoriasisRecurrent fever, increased CRP level, pericarditis, myocarditis, intestinal vasculitis, renal microaneurysm, peripheral neuropathy, death from visceral complicationsNodule on the legYesDeep dermis medium-sized arteryAcute cPANDeep dermis medium-sized artery—6Livedo reticularisIncreased CRP level, ischemic strokes, hepatosplenomegaly, low IgM level, negative vaccinal serology resultsNo biopsy—————7/17/2Livedo racemosaLeg nodulesRecurrent fever, increased CRP level, arthralgia, abdominal pain, hepatosplenomegaly, epilepsyNodule on the legNodule on the legNoNo——Reparative cPANNoDeep dermis medium-sized artery—Septal panniculitis8/1Livedo racemosaDigital necrosisLeg nodulesRecurrent fever, increased CRP level, ischemic stroke, abdominal pain, psychosis, pericarditisNodule on the legNo—Subacute cPANDeep dermis medium-sized artery—cPAN, Cutaneous periarteritis nodosa; CRP, C-reactive protein; ENT, ear, nose, and throat; TIA, transient ischemic attack.∗ Definitions of the cPAN stages by Ishibashi and Chen4Ishibashi M. Chen K.-R. A morphological study of evolution of cutaneous polyarteritis nodosa.Am J Dermatopathol. 2008; 30: 319-326Crossref PubMed Scopus (39) Google Scholar are as follows. Acute: endothelial loss and fibrin thrombi with neutrophil infiltration without obvious internal elastic lamina disruption and medial fibrinoid necrosis. Subacute: mixed-cell infiltrates showing a unique intimal target-like fibrinoid necrosis with fibrinoid leakage extending through the disrupted sites of the internal elastic lamina to the media. Reparative: intimal fibroblastic proliferation and perivascular neovascularization with predominant infiltrates of histiocytes and lymphocytes. Healed: minimal cellular inflammation with occlusive intimal thickening. Thrombosis was defined as complete occlusion of the vascular lumen by a cluster of fibrin. Open table in a new tab cPAN, Cutaneous periarteritis nodosa; CRP, C-reactive protein; ENT, ear, nose, and throat; TIA, transient ischemic attack. Cutaneous manifestations (Fig 1) were the first symptoms of DADA2 in 3 of 8 patients. Livedo was observed in all cases and was of the racemosa subtype in 7 of 8 patients, with mostly a large pattern (6/8). It involved both legs and arms in all patients, extending to the abdomen or trunk in 3 patients. It was palpable in 1 patient. Other cutaneous manifestations included leg nodules (n = 7, nonspecific or erythema nodosum–like lesions), leg ulcers (n = 3), Raynaud phenomenon (n = 2), atrophie blanche (n = 2), digital necrosis (n = 2), erythematous foot papules (n = 1), and psoriasis (n = 1). Overall, 12 skin biopsy samples from 7 patients were reviewed (Table I and Fig 1). cPAN was identified in 4 of 7 patients. In patients 3 and 4, skin biopsy samples showed thrombosis of dermal and/or hypodermal capillaries, without vasculitis. Although subacute cPAN was also observed in a skin biopsy sample from patient 4, patient 3 had only isolated thrombosis. Here, we portrayed the dermatologic spectrum of patients with DADA2, thus contributing to its better recognition. Livedo was observed in all cases and was mostly racemosa, extensive, and with a large reticular pattern. Differentiating between DADA2 and antiphospholipid-negative Sneddon syndrome (as in patient 4) may be challenging because both may present with livedo and stroke.5Francès C. Papo T. Wechsler B. Laporte J.L. Biousse V. Piette J.C. Sneddon syndrome with or without antiphospholipid antibodies. A comparative study in 46 patients.Medicine (Baltimore). 1999; 78: 209-219Crossref PubMed Scopus (171) Google Scholar Although skin biopsy samples of patients with DADA2 most frequently showed vasculitis, 2 patients in our series showed capillary thrombosis, such as in Sneddon syndrome.5Francès C. Papo T. Wechsler B. Laporte J.L. Biousse V. Piette J.C. Sneddon syndrome with or without antiphospholipid antibodies. A comparative study in 46 patients.Medicine (Baltimore). 1999; 78: 209-219Crossref PubMed Scopus (171) Google Scholar Importantly, 3 of 7 patients did not have vasculitis on skin biopsy. The site and depth of biopsy is probably important. Indeed, although we found nonspecific features in 2 superficial biopsies of livedo without analyzable hypodermis, cPAN was more frequently identified in biopsy samples taken from nodules. Overall, livedo racemosa with a large branch pattern, nodules, or ulcerations in a context of neurovascular events, recurrent fever, low immunoglobulin M levels, and pediatric onset is suggestive of DADA2. Although cPAN on skin biopsy is suggestive of DADA2, its absence or the presence of thrombotic features does not exclude the diagnosis.

Necrotizing infundibular crystalline folliculitis is a rare condition characterized by folliculocentric waxy papules in the seborrheic areas of adult patients, with intrafollicular filamentous birefringent crystalline deposits as the histopathologic clue. Although the real pathogenesis of necrotizing infundibular crystalline folliculitis remains unclear, the intrafollicular material seems to be derived from an interaction between such superficial microorganisms as gram-positive bacteria (Propionibacterium acnes, Staphylococcus spp), Malassezia yeasts, and sebaceous lipids. Topical or systemic antiacne agents or antimycotics appear to be effective therapy.

Langerhans cell (LC) histiocytoma is a neonatal tumor that often consists of a single, ulcerated nodule. Systemic involvement is rare, and LC histiocytoma is considered to be a variant of congenital, self-healing LC histiocytosis (also referred to as Hashimoto-Pritzker disease). In view of its low prevalence. LC histiocytoma is not always diagnosed in a clinical examination and requires histological confirmation. Furthermore, the histological and molecular features of LC histiocytoma have not been well characterized. Here, we report on 6 cases of this rare disease and review the corresponding literature. LC histiocytoma differs from classical self-healing LC histiocytosis with regard to the pathological features; we found that LC histiocytoma was associated with massive infiltration by histiocytes of various sizes and shapes (although often large) throughout the dermis and the superficial subcutis. Epidermotropism was rare, mitotic figures were not inconspicuous, and necrotic or calcified areas were often present. Immunohistochemical assessment revealed a mixture of different types of histiocytes (with CD1a(+) CD207(+), CD1a(+) CD207(-), and CD1a(-) CD207(-), CD163(+) cells). Genetic testing was performed in 5 cases; it revealed a BRAF mutation (p.V600E and p.485_490delinsF) in 2 cases, a HRAS mutation (p.T58I) in 1 case, a combination of 2 PTEN mutations in another case (p.I224M and p. R234W), and no mutations in the fifth case. All the lesions regressed spontaneously, and none recurred during follow-up.

We report on 4 children who presented with aseptic panniculitis associated with inherited immunodeficiency. Three patients had a B-cell immunodeficiency resulting from mutations in the TRNT1 and NF-κb2 genes (no mutation was found in the third patient), and 1 had a T-cell deficiency (mutation in the LCK gene). Panniculitis occurred before the age of 2 years in the 4 patients and preceded the onset of recurrent infections because of immunodeficiency in 2. It presented either as nodules, which resolved spontaneously within 1 to 2 weeks (3 patients), or chronic ulcerative lesions (1 patient) associated with unexplained fever and elevated acute phase reactants, without evidence of infection or high-titer autoantibodies. Febrile nodules relapsed in 2 patients, and recurrent attacks of unexplained fever (without relapse of panniculitis) occurred in the third. Skin biopsy revealed predominantly lympho-histiocytic or septal neutrophilic panniculitis in 1 and 3 patients, respectively. Panniculitis was associated with dermal involvement in the 4 patients. Patients with B-cell deficiency received monthly intravenous immunoglobulin replacement. Two patients who underwent bone marrow transplant died of bone marrow transplant-related complications. The 2 remaining patients had persistent, mild autoinflammatory disease, which did not require specific treatment. In these cases, the need for careful immunologic evaluation of patients who present with unexplained panniculitis, especially early-onset panniculitis before the age of 2 years, is highlighted.