Inborn Errors of Immunity (IEI) comprise several genetic anomalies that affect different components of the innate and adaptive responses, predisposing to infectious diseases, autoimmunity and malignancy. Different studies, mostly in adults, have reported a higher prevalence of cancer in IEI patients. However, in part due to the rarity of most of these IEI subtypes (classified in ten categories by the Primary Immunodeficiency Committee of the International Union of Immunological Societies), it is difficult to assess the risk in a large number of patients, especially during childhood. To document the cancer prevalence in a pediatric cohort from a single referral institution, assessing their risk, together with the type of neoplasia within each IEI subgroup. An extensive review of clinical records from 1989 to 2022 of IEI patients who at some point developed cancer before the age of sixteen. Of a total of 1642 patients with IEI diagnosis, 34 developed cancer before 16 years of age, showing a prevalence (2.1

Background: Rare histiocytic disorders (RHDs) are diverse myeloid neoplasms that include Juvenile xanthogranuloma (JXG), Erdheim-Chester Disease (ECD), Rosai-Dorfman disease (RDD), Malignant histiocytoses (MH), ALK+ histiocytosis, indeterminate cell histiocytosis (ICH) and mixed histiocytosis (MXH). Methods: IRHDR data were collected retrospectively and prospectively including clinical features, diagnosis with central pathology (CP) review, treatments and outcomes. Descriptive statistics of data registered during the first 9 years are presented. Results: From April 2015 - June 2024, 214 patients were enrolled, 133 completed CP review; 111 confirmed RHD and 22 excluded. We present 192 RHD patients; median age at diagnosis was 11 years (0.11-77 years), 112 (58.3%) were males. JXG family patients (n=66): 2 KRAS+, 1 BRAF-other+, 1 MAP2K1+, 1 CSFR1+. Thirty-six were cutaneous (2 had JMML): 11 (31%) did well with observation, and 13 (36%) severe cases responded well to surgery +/- steroids. One progressive nodular had partial response (PR) to MEK-inhibitor (MEK-I). Five had reticulohistiocytoma: 2 had observation (complete response - CR), and 2 oral chemotherapy (1 PR; 1 resistant had PR after everolimus). Sixteen were systemic: 3 (19%) had vinblastine/steroids - LCH-III (CR), 1 surgery (CR), and 2 observation (1 CR; 1 stable disease - SD); 7 (44%) had relapsed/refractory (R/R) disease: 2 had cladribine or surgery (PR), and 5 others were refractory to cladribine or clofarabine (1 PR after MEK-I). Two systemic JXG were post-ALL, 1 died from toxicity and 1 is alive (SD). Three had adult JXG: 2 musculoskeletal had surgery/observation (CR), and 1 cutaneous had RET-kinase inhibitor (CR). Five intraocular: 3 had surgery (CR/PR), 2 resistant to oral chemotherapy had MEK-I (1 CR; 1 SD after intrarterial melphalan). ECD patients (n=41): 16 BRAF-V600E+, 3 MAP2K1+, 1 KRAS+. Five were localized, 19 systemic, and 15 CNS. BRAF/MEK-I induced more responses (81% overall response rate - ORR) than conventional therapies (interferon-α, chemotherapy, anakinra, radiation; 55% ORR) as first-line or salvage therapy. RDD patients (n=51): 2 BRAF-V600E+, 2 KRAS+, 1 MAP2K1+. Twenty-four were nodal: 7 (29%) had observation (SD), 12 (50%) had surgery +/- steroids (variable responses), 1 had clofarabine (PR), and 1 had chemotherapy followed by MEK-I (died from progressive disease - PD). Twenty-seven were systemic: 11 (41%) had oral chemotherapy (73% ORR), 3 (27%) R/R had cladribine (all PR); 2 had surgery (75% ORR), 5 observation (40% ORR); 2 had indomethacin or radiotherapy (SD); 5 (19%) R/R received BRAF/MEK-I (60% ORR); 1 refractory to surgery and cladribine (died from PD). MH patients (n=16): 3 KRAS+, 1 BRAF-V600E+. Twelve histiocytic subtype, 2 Langerhans cell, 1 interdigitating cell and 1 indeterminate cell tumour. Eight MH were localized: 3 had surgery +/- chemotherapy (2 CR, 1 relapse had PDL-1 inhibitor), 3 steroids +/- chemotherapy (1 CR, 1 SD, 1 PD with CR after cladribine). One R/R to cladribine/radiotherapy (SD), and 1 post-ALL MH was refractory to cladribine (died from PD). Seven MH were systemic: 3 had ALL-like therapy (2 CR, 1 SD), 2 chemotherapy + steroids (1 SD, 1 died from PD), and 1 had MEK-I (PR then relapsed). One with CNS+ MH had surgery followed by BRAF/MEK-I (CR). ALK+ histiocytosis patients (n=7): 5 localized: 2 musculoskeletal had observation (1 CR, 1 SD), 1 ocular had crizotinib (PR), 1 localized to the trachea had surgery (CR). Two CNS+ had LCH-III +/- surgery (1 CR; 1 R/R had PR to lorlatinib then relapsed). ICH patients (n=6): 1 BRAF-V600E+, 1 BRAF-other+, 1 MAP2K1+. 100% ORR was seen in 4 localized with observation or steroids, and 2 systemic/CNS with LCH-III. MXH patients (n=5): 2 BRAF-V600E+, 1 BRAF-other+, 1 MAP2K1+. One had localized RDD/LCH, 4 were systemic: 3 ECD/LCH, 1 ECD/RDD. Most MXH were refractory to conventional therapies, with durable responses to BRAF/MEK-I. After a median follow-up of 29.6 months, 94.8% of patients (n=182) are alive in CR/SD. Event-free survival is 84%; 28 (15%) relapsed. Five patients died, 4 from PD, and 1 from toxicity. Conclusions:RHDs are characterized by pathological, clinical and molecular diversity, with variable responses to conventional therapies. Most refractory systemic cases respond to ALK/BRAF/MEK-I. Further mutational analysis may identify novel targeted therapies, which could be helpful for resistant RHDs.

CARD11-associated diseases are monogenic inborn errors of immunity involving immunodeficiency, predisposition to malignancy and immune dysregulation such as lymphoproliferation, inflammation, atopic and autoimmune manifestations. Defects in CARD11 can present as mutations that confer a complete or a partial loss of function (LOF) or contrarily, a gain of function (GOF) of the affected gene product. We report clinical characteristics, immunophenotypes and genotypes of 15 patients from our center presenting with CARD11-associated diseases. Index cases are pediatric patients followed in our immunology division who had access to next generation sequencing studies. Variant significance was defined by functional analysis in cultured cells transfected with a wild type and/or with mutated h CARD11 constructs. Cytoplasmic aggregation of CARD11 products was evaluated by immunofluorescence. Nine index patients with 9 unique heterozygous CARD11 variants were identified. At the time of the identification, 7 variants previously unreported required functional validation. Altogether, four variants showed a GOF effect as well a spontaneous aggregation in the cytoplasm, leading to B cell expansion with NF-κB and T cell anergy (BENTA) diagnosis. Additional four variants showing a LOF activity were considered as causative of CARD11-associated atopy with dominant interference of NF-kB signaling (CADINS). The remaining variant exhibited a neutral functional assay excluding its carrier from further analysis. Family segregation studies expanded to 15 individuals the number of patients presenting CARD11-associated disease. A thorough clinical, immunophenotypical, and therapeutic management evaluation was performed on these patients (5 BENTA and 10 CADINS). A remarkable variability of disease expression was clearly noted among BENTA as well as in CADINS patients, even within multiplex families. Identification of novel CARD11 variants required functional studies to validate their pathogenic activity. In our cohort BENTA phenotype exhibited a more severe and expanded clinical spectrum than previously reported, e.g., severe hematological and extra hematological autoimmunity and 3 fatal outcomes. The growing number of patients with dysmorphic facial features strengthen the inclusion of extra-immune characteristics as part of the CADINS spectrum. CARD11-associated diseases represent a challenging group of disorders from the diagnostic and therapeutic standpoint, especially BENTA cases that can undergo a more severe progression than previously described.

INTRODUCTION:The clinical value of lymph node sampling in Wilms tumor (WT) lies in its ability to accurately determine lymph node (LN) involvement. LN yield (LNY) is used as a valuable tool to measure LN retrieval, and a minimum of 6 LNs is one of the current recommendations. In patients who are managed with the SIOP strategy, preoperative chemotherapy decreases the retrieval of LN during surgery resulting in lower LNY values.PURPOSE:To determine the mean LNY and to analyze survival outcomes in patients with WT who underwent preoperative chemotherapy at a single center.METHODS:We performed a retrospective chart review of all patients between 6 months and 12 years of age with unilateral WT who underwent preoperative chemotherapy between 2010 and 2018. Patients with bilateral WT or without preoperative chemotherapy were excluded. Collected data included: demographics, tumor volume, tumor histopathology, number of LNs collected (LNY), presence or absence of tumor in the retrieved LNs, and disease stage according to these results. Kaplan Meier curves were calculated to estimate 5-year event-free survival (EFS) and overall survival (OS).RESULTS:95 patients with a median follow-up of 25 months were included in the study. A total of 19 patients underwent laparoscopic surgery. Mean LNY for the entire cohort was 3.26 (95% CI, 2.4-3.6; SD, 3.62). Six patients (6.3%) had at least one positive LN. The estimated 5-year OS was 89.3% (95% CI, 82.1%-96.5%). EFS was 79.8 (95% CI, 74.8%-84.8%). Recurrence rate was 20% (n: 19). Four patients (4.2%) developed local recurrence and 15 patients (15.7%) developed pulmonary recurrence. The initial mean LNY in patients that relapsed was 4.16 (95% CI, 2.2-5.8; SD: 4.18), which was higher than in patients who did not relapse (LNY: 3; 95% CI, 2.33-3.67; SD, 3.39). No recurrences or deaths occurred in the laparoscopic group.DISCUSSION:The identification of a minimum LNY (i.e. threshold) to minimize the risk of harboring occult metastatic disease has been proposed to standardize the surgical procedure. Preliminary results in this study suggest that a limited LNY with acceptable survival outcomes is a possible scenario in patients treated according to the SIOP protocol. Systematic LN sampling to reduce the rate of false negatives is still strongly recommended.CONCLUSION:Our cohort presented with a relatively low LNY compared to standard recommendations. Our EFS, however, remained acceptable. Multivariate analysis would be necessary to determine the actual role of LN sampling as an isolated prognostic factor in unilateral WT.

Targeted therapies with MAPK inhibitors have proven to modulate the clinical manifestations of patients with Langerhans cell histiocytosis (LCH). We explored the presence of BRAFV600E mutation in our cohort of patients with LCH and cholestasis, sclerosing cholangitis, or liver fibrosis that presented resistance to chemotherapy. The BRAFV600E mutation was detected either in the diagnosis (skin and bone) or liver biopsy in our cohort of 13 patients. Thus, we observed a high incidence of BRAFV600E mutation in 100% either in diagnostic biopsy (skin and bone) or liver biopsy in patients with progressive liver disease, sequela, or liver transplant requirement.

Histiocytic sarcoma (HS) is a rare malignant neoplasm, with morphological and immunophenotypic characteristics similar to mature histiocytes, representing less than 1% of all hematological malignancies. HS can be associated with lymphomas, myelodysplasia, and some leukemias. Its clinical presentation varies from being localized to presenting systemic compromise. We present the clinical case of an 11-year-old boy with a 6-year OLD history of Acute Lymphoblastic Leukemia B, in complete continuous remission (CCR). Two years after finishing his treatment, the patient presents symptoms of abdominal pain and vomiting, intermittent fever. Abomino-pelvic CT with expansive mass at the mesenteric level. With an anatomopathological diagnosis by biopsy of histiocytic sarcoma, he performed 2 cycles of preoperative chemotherapy, followed by a right hemicolectomy with complete resection. Due to compromised microscopic margins and infiltrated lymph nodes, it was decided to continue chemotherapy, completing two more cycles. Seven months after the diagnosis, 2 metabolically active retroperitoneal lymphadenopathies were confirmed by PET-CT and they were completely resected. With PET-CT control 9 months after the last surgery, there was no evidence of hyper-uptake lymphadenopathy. He currently remains in CCR 2 years after diagnosis.