The presence of enlarged epithelioid/spindled nests located deep in the reticular dermis of a biphasic melanocytic neoplasm can mimic melanoma arising in a pre‐existing nevus, causing over‐interpretation of malignancy. We aimed to define the clinicopathologic significance of epithelioid/spindled nests in melanocytic nevi. Retrospectively using clinical and histologic information, we characterized 121 patients with a single lesion showing epithelioid/spindled melanocytes in the reticular dermis or subcutaneous fat, surrounded by melanophages, sometimes blending in with the adnexa. The majority of nevi occurred in women in the ages of 10 to 39 years, where the most frequent presentation was a changing mole. While 78% of the lesions displayed an anatomic (Clark’s) level of IV‐V, there was no ulceration, significant regression or inflammation. Up to 2 mitoses were found in only 12% of the cases, not correlating with the severity of cytological atypia. No recurrence or metastasis occurred during 45.5 months (mean) of clinical follow up in 26 patients. Notwithstanding the deep dermal extension, these findings suggest a benign histopathology and clinical outcome. Having compared the overlapping histopathology and clinical features between deep penetrating/clonal nevus and combined nevus, we posit that “inverted type‐A nevus” might be considered a variant of the two.

We report a case of a 68-year-old white woman presenting with 5 sebaceous neoplasms, ranging from sebaceous adenoma to sebaceoma on histopathology. Despite the lack of a personal cancer history, her multiple sebaceous neoplasms and a paternal history of colon cancer prompted testing her sebaceous adenomas for microsatellite instability (MSI) by immunohistochemistry. The results showed retained nuclear expressions of MLH1 and PMS2 while MSH2 and MSH6 proteins were absent. The tumor infiltrating lymphocytes expressed both MSH2 and MSH6, providing reliable internal positive controls. Having a high probability for MSI, she was found to be heterozygous for a germline point mutation in MSH2 gene, where a pathologic variant, c.1165C > T (p.Arg389*), determined by sequencing confirmed Muir-Tone syndrome (MTS). On further genetic counseling recommendations, one of her 2 sons was found to have colon cancer in the context of his MTS. In this article, we highlight and review the implications of MSI testing by both immunohistochemistry and sequencing as they relate to confirming the diagnosis of a suspected case of MTS.

Histologic differentiation of melanoma in situ (MIS) from solar keratosis on chronically sun‐damaged skin is challenging. The first‐line immunostain is usually MART‐1/Melan‐A, which can exaggerate the epidermal melanocytes, causing a diagnostic pitfall for MIS. By comparing MART‐1 and SOX10 immunostaining, we scored the percentage of epidermal melanocytes per 2‐mm diameter fields in pigmented actinic keratosis ( n = 16), lichenoid keratosis ( n = 7), junctional melanocytic nevus ( n = 6), keratosis with atypical melanocytic proliferation ( n = 17) and MIS ( n = 10). These cases represented an older population (68 years median age) and the head and neck (50%) was the most common anatomic site. MART‐1 score was significantly higher than SOX10 ( P value <.05) in solar keratoses, but showed no difference in detecting melanocytic proliferations, demonstrating their equal detection rate of melanocytes. The sensitivity of both MART‐1 and SOX10 was 100%, while their specificities were 17% and 96%, respectively. These results show that SOX10 is more specific than MART‐1 in distinguishing epidermal melanocytes on sun‐damaged skin by avoiding overdiagnosis of melanoma.

Syphilis is a systemic, multistage, sexually transmitted infection caused by the highly invasive spirochetal bacterium, Treponema pallidum, subspecies pallidum. In the United States, the annual rate of primary and secondary syphilis (SS) between 2002 and 2016 has increased from 2.1 to 8.7 cases per 100,000.1 Gestational and congenital syphilis cases have also increased in the last few years. There is no evidence of a change in T pallidum susceptibility to penicillin as an explanation for the significant increase in the number of syphilis cases in the United States.

A comprehensive repertoire of human microRNAs (miRNAs) that could be involved in early melanoma invasion into the dermis remains unknown. To this end, we sequenced small RNAs (18–30 nucleotides) isolated from an annotated series of invasive melanomas (average invasive depth, 2.0 mm), common melanocytic nevi, and matched normal skin (n=28). Our previously established bioinformatics pipeline identified 765 distinct mature known miRNAs and defined a set of top 40 list that clearly segregated melanomas into thin (0.75 mm) and thick (2.7 mm) groups. Among the top, miR-21-5p, let-7b-5p, let-7a-5p, miR-424-5p, miR-423-5p, miR-21-3p, miR-199b-5p, miR-182-5p, and miR-205-5p were differentially expressed between thin and thick melanomas. In a validation cohort (n=167), measured expression of miR-21-5p and miR-424-5p, not previously reported in melanoma, were significantly increased in invasive compared with in situ melanomas (P<0.0001). Increased miR-21-5p levels were significantly associated with invasive depth (P=0.038), tumor mitotic index (P=0.038), lymphovascular invasion (P=0.0036), and AJCC stage (P=0.038). In contrast, let-7b levels were significantly decreased in invasive and in situ melanomas compared with common and dysplastic nevi (P<0.0001). Decreased let-7b levels were significantly associated with invasive depth (P=0.011), Clark's level (P=0.013), ulceration (P=0.0043), and AJCC stage (P=0.011). These results define a distinct set of miRNAs associated with invasive and aggressive melanoma phenotype.

The International Knockout Mouse Consortium was formed in 2007 to inactivate (“knockout”) all protein-coding genes in the mouse genome in embryonic stem cells. Production and characterization of these mice, now underway, has generated and phenotyped 3,100 strains with knockout alleles. Skin and adnexa diseases are best defined at the gross clinical level and by histopathology. Representative retired breeders had skin collected from the back, abdomen, eyelids, muzzle, ears, tail, and lower limbs including the nails. To date, 169 novel mutant lines were reviewed and of these, only one was found to have a relatively minor sebaceous gland abnormality associated with follicular dystrophy. The B6N(Cg)-Far2tm2b(KOMP)Wtsi/2J strain, had lesions affecting sebaceous glands with what appeared to be a secondary follicular dystrophy. A second line, B6N(Cg)-Ppp1r9btm1.1(KOMP)Vlcg/J, had follicular dystrophy limited to many but not all mystacial vibrissae in heterozygous but not homozygous mutant mice, suggesting that this was a nonspecific background lesion. We discuss potential reasons for the low frequency of skin and adnexal phenotypes in mice from this project in comparison to those seen in human Mendelian diseases, and suggest alternative approaches to identification of human disease-relevant models.

Porocarcinoma is a rare malignant neoplasm of the acrosyringium with metastatic potential that most commonly presents on the acral skin in older adults (mean age = 72 years). We present the case of a 43-year-old woman who developed a rapidly growing de novo porocarcinoma on the scalp with an unusual oncocytic appearance. The tumor consisted of benign eccrine poroma that arose from the epidermis and broad pushing borders with minimal cytological atypia but ample eosinophilic cytoplasm with numerous mitotic figures. Although some tumors may appear deceptively bland, the histologic recognition of pushing/infiltrative borders and mitotic figures are helpful to make the appropriate diagnosis of carcinoma. This lesion was treated with Mohs micrographic surgery and the patient remained free of recurrence after more than 2 years. It is important to recognize the eosinophilic variants of eccrine porocarcinoma because it can histologically mimic a squamous cell carcinoma.

Objectives: Histologic and molecular heterogeneity is well recognized in malignant melanoma; however, the diversity of expression of new and classic melanoma markers has not been correlated in serial sections of metastases.Methods: We examined and correlated the expression of microphthalmia transcription factor (MITF) with its transcriptional targets, including melastatin (MLSN1/TRPM1), pigment epithelium-derived factor (SERPINF1/PEDF), SILV/PMEL17/GP100 (human melanoma black 45 [HMB-45]), and melanoma antigen recognized by T cells 1 (MART-1)/MLANA, in 13 melanoma metastases in lymph nodes of 13 patients. The expression levels and patterns of marker expression were recorded by a semiquantitative, 4-point ordinal reactivity method.Results: Our results showed a consistently robust and diffuse expression of MITF protein in 12 (92%) of 13 metastatic tumors compared with variable expression of MLSN1 (46%) messenger RNA or PEDF (75%), HMB-45 (54%), and MART-1 (46%) proteins.Conclusions: Overall, in melanoma lymph node metastases, MITF protein expression was not tightly correlated with its gene targets. Moreover, the immunoreactivity for MITF, compared with MART-1 and HMB-45, was retained, supporting immunohistochemical detection of MITF as a more sensitive method of detecting metastatic melanoma.

Some melanocytic tumors can be histologically ambiguous causing diagnostic difficulty, which could lead to overtreatment of benign lesions with an unwarranted psychological distress or undertreatment of malignant cancers. Previously, we demonstrated that significantly decreased miR-211 expression in melanomas compared with melanocytic nevi could accurately discriminate malignant from benign tumors. Herein we show microRNA in situ hybridization for fluorescent detection of miR-211, suitable for paraffin-embedded tissues in 109 primary melanocytic tumors. miR-211 expression was significantly lower in melanomas vs nevi (P<0.0001), and receiver operating characteristic curve (area under the curve=0.862) accurately discriminated melanomas from nevi with 90% sensitivity and 86.2% specificity. Qualitatively, all dysplastic nevi expressed miR-211 at high (86%) and low (14%) levels, independent of the degree of nuclear atypia. All 35 melanocytic tumors with Spitz morphology expressed miR-211 independent of morphological classification, where clinical follow-up of these patients showed no recurrence at the site or metastasis in mean and median of 3 (ranging 2–5) years. Moreover, a decision tree learning analysis selected age and miR-211 miRNA in situ hybridization as the predictive variables for benign or malignant outcome in 88 patients correctly classified 92% (81 out of 88) of cases as proven by receiver operating characteristic curve (area under the curve=0.9029). These results support miR-211 as a leading miRNA candidate for melanoma diagnosis and miRNA in situ hybridization as a uniquely uncomplicated ancillary test.

BACKGROUND:There have been repeated initiatives to produce standard nosologies and terminologies for cutaneous disease, some dedicated to the domain and some part of bigger terminologies such as ICD-10. Recently, formally structured terminologies, ontologies, have been widely developed in many areas of biomedical research. Primarily, these address the aim of providing comprehensive working terminologies for domains of knowledge, but because of the knowledge contained in the relationships between terms they can also be used computationally for many purposes.RESULTS:We have developed an ontology of cutaneous disease, constructed manually by domain experts. With more than 3000 terms, DermO represents the most comprehensive formal dermatological disease terminology available. The disease entities are categorized in 20 upper level terms, which use a variety of features such as anatomical location, heritability, affected cell or tissue type, or etiology, as the features for classification, in line with professional practice and nosology in dermatology. Available in OBO flatfile and OWL 2 formats, it is integrated semantically with other ontologies and terminologies describing diseases and phenotypes. We demonstrate the application of DermO to text mining the biomedical literature and in the creation of a network describing the phenotypic relationships between cutaneous diseases.CONCLUSIONS:DermO is an ontology with broad coverage of the domain of dermatologic disease and we demonstrate here its utility for text mining and investigation of phenotypic relationships between dermatologic disorders. We envision that in the future it may be applied to the creation and mining of electronic health records, clinical training and basic research, as it supports automated inference and reasoning, and for the broader integration of skin disease information with that from other domains.

Primary melanoma of the genitourinary tract represents ≤1% of all melanomas and is a highly aggressive malignancy, usually presenting at an advanced stage. Primary urethral melanomas are often amelanotic, leading to difficulties in early clinical diagnosis and biopsy delays. Herein, we present the clinical follow-up and histopathology of two female patients with microscopic invasion of the urethral ducts, not illustrated by previous reports. This finding, verified by appropriate immunohistochemical markers, can be a useful clue in diagnosing amelanotic melanoma of the genitourinary tract. The pathology reporting for urethral melanoma should include the depth of invasion, mitotic index, the status of resection margins, perineural invasion and lymphatic invasion since they will likely have a bearing on the tumor's biological behavior. Herein, we report two female patients with urethral melanoma exhibiting urethral duct invasion. Moreover, we discuss pertinent histopathological and immunohistochemical features, along with oncogene mutational typing that may aid in confirming the diagnosis and identifying molecular target(s).

Mus pahari is a wild-derived, inbred mouse strain. M. pahari colony managers observed fragility of this strain's skin resulting in separation of tail skin from the mouse if handled incorrectly. Tail skin tension testing of M. pahari resulted in significantly lowered force threshold for caudal skin rupture and loss in comparison to closely related inbred mouse species and subspecies and even more than a model for junctional epidermolysis bullosa. Histologically, the tail skin separated at the subdermal level with the dermis firmly attached to the epidermis, excluding the epidermolysis bullosa complex of diseases. The dermal collagen bundles were abnormally thickened and branched. Elastin fiber deposition was focally altered in the dermis adjacent to the hair follicle. Collagens present in the skin could not be differentiated between the species in protein gels following digestion with pepsin. Together these data suggest that M. pahari have altered extracellular matrix development resulting in separation of the skin below the level of the dermis with moderate force similar to the African spiny mouse (Acomys spp.).

Over the last decade, large-scale, primarily N-ethyl-N-nitrosourea (ENU)-based, chemical mutagenesis projects (Clark et al., 2004Clark A.T. Goldowitz D. Takahashi J.S. et al.Implementing large-scale ENU mutagenesis screens in North America.Genetica. 2004; 122: 51-64Crossref PubMed Scopus (77) Google Scholar) inspired the development of high-throughput, broad-coverage means to analyze mutant mouse phenotypes. The dark skin mutations, GnaqMhdadsk1 and GnaqMhdadsk10, arose in just such an ENU mutagenesis screen. These dark skin mutations are due to missense mutations in the Gnaq gene (Fitch et al., 2003Fitch K.R. McGowan K.A. van Raamsdonk C.D. et al.Genetics of dark skin in mice.Genes Dev. 2003; 17: 214-228Crossref PubMed Scopus (121) Google Scholar, Van Raamsdonk et al., 2004Van Raamsdonk C.D. Fitch K.R. Fuchs H. et al.Effects of G-protein mutations on skin color.Nat Genet. 2004; 36: 961-968Crossref PubMed Scopus (143) Google Scholar). A third dominant mutation, GnaqM1J, arose in an ENU mutagenesis screen using the C57BL/6J mouse strain at the Jackson Laboratory (Bar Harbor, ME). We report here the phenotype and molecular defect of this new allelic mutation. The GnaqM1J deviant mice presented with abnormally pigmented tails inherited in a dominant manner (Figure 1a). Further observations indicated pigmentary changes throughout the skin of deviant mice (Figure 1b, i–iv). GnaqM1J mice exhibited unusually dark pigmented tails (Figure 1b, i), ears (Figure 1b, ii), lower legs and foot pads (Figure 1b, iii), and dorsal skin (Figure 1b, iv) as compared with wild-type littermates. To define histologic lesions, a complete set of tissues were harvested from three males and three females, mutant and control, 12-week-old mice and processed routinely. Paraffin sections were stained with hematoxylin and eosin and examined by an experienced board-certified veterinary anatomic pathologist (JPS) (Silva and Sundberg, 2012Silva K. Sundberg J. Necropsy methods. Academic Press, London, UK2012: 779-806Crossref Scopus (18) Google Scholar). Histologic analysis of tail skin taken from wild-type C57BL/6J mice demonstrated low levels of interfollicular epidermal pigment and dermal hyperpigmentation (Figure 2a and b). By contrast, GnaqM1J mutant mice tail sections exhibited high levels of dermal hyperpigmentation and interfollicular epidermal pigmentation in similar regions of the tail (Figure 2c and d). This was more evident in cross-sections of GnaqM1J tail skin (Figure 2e, arrows), especially in oblique sections of the dermis (Figure 2f). In addition, sections through ventral leg skin (Figure 2g and h) and foot pads with eccrine glands (Figure 2i and j) revealed dermal hyperpigmentation but no interfollicular pigment in the epidermis. Also, wild-type dorsal skin sections and hair follicles (Figure 2k, i–iii) exhibited no pigment evident in the dermal papilla or residual pigment in the dermis below the hair follicle in the fibrous track of the former catagen follicle, whereas dorsal skin sections from mutant mouse (Figure 2l, i–iii) exhibited abnormal pigmentation in the dermal papilla region extending into the underlying dermis in the fibrous streak remaining at the end of catagen. Immunohistochemistry was also performed whereby paraffin sections from mutant and control animals were stained with antibodies specific to the following antigens: Smooth Muscle Actin, CD31, LYVE1, and VEGFA. The immunohistochemical stains were used to examine vascular abnormalities in these mice, yet no differences were observed between mutant and control mice (data not shown). Single nucleotide polymorphism mapping was performed to isolate the genomic region containing the mutant allele by backcrossing the original C57BL6/J deviant mouse to the inbred mouse strain FVB/NJ. Mapping studies revealed linkage to proximal mouse chromosome 19 near single nucleotide polymorphism marker 21,436,276 base pair (GRCm38) with a logarithm of odds score equal to 5.3. Targeted exome sequencing of Gnaq identified a single base pair variant resulting in an A to G missense mutation in exon 2 at 16,219,611 base pair (Figure 1c). This variant is predicted to result in a threonine to alanine change at amino acid 54 (T54A). GNAQ consists of an alpha-helical domain, three flexible switch domains, and a GTPase domain (Kumar et al., 2009Kumar P. Henikoff S. Ng P.C. Predicting the effects of coding non-synonymouse variant on protein function using the SIFT algorithm.Nat Protoc. 2009; 4: 1073-1081Crossref PubMed Scopus (5001) Google Scholar). The T54A resides in the N-terminus of the alpha-helical domain. The “Sorting Tolerant from Intolerant” algorithm identified the T54A variant as a deleterious mutation in the helical domain of GNAQ (score 0.01), which may affect proper domain functioning (The UniProt Consortium, 2014The UniProt ConsortiumActivities at the universal protein resource (UniProt).Nucleic Acids Res. 2014; 42: D191-D198Crossref PubMed Scopus (1058) Google Scholar) (Figure 1c). Previous ENU-induced mutations, GnaqMhdadsk1 and GnaqMhdadsk10, affected the C-terminus of the alpha-helical domain and GTPase-domain, respectively (Fitch et al., 2003Fitch K.R. McGowan K.A. van Raamsdonk C.D. et al.Genetics of dark skin in mice.Genes Dev. 2003; 17: 214-228Crossref PubMed Scopus (121) Google Scholar, Van Raamsdonk et al., 2004Van Raamsdonk C.D. Fitch K.R. Fuchs H. et al.Effects of G-protein mutations on skin color.Nat Genet. 2004; 36: 961-968Crossref PubMed Scopus (143) Google Scholar). All three ENU-induced mutations, affecting different areas of the GNAQ protein, resulted in similar, but not identical, pigmentary changes to the skin of affected mice. Also, the differences in phenotype between the previously described alleles (GnaqMhdadsk1 and GnaqMhdadsk10) and GnaqM1J may be due to genetic background of the mouse strain, whereby the previous alleles were found on the C3HeB/FeJ strain, with a wild-type agouti locus (A/A), and the new allele was found on the C57BL/6J background, with a mutant agouti allele (a/a) producing only black pigment. A multitude of signaling pathways operate in the skin, whose coordination is essential for proper skin development and differentiation (see Supplementary Figures 1 and 2, online). However, the molecular mechanisms governing these processes are still largely unknown. We report here a new, publicly available ENU-induced mutant (GnaqM1J) that results in similar, but more extensive, skin hyperpigmentation defects as the GnaqMhdadsk1 and GnaqMhdadsk10 alleles (Fitch et al., 2003Fitch K.R. McGowan K.A. van Raamsdonk C.D. et al.Genetics of dark skin in mice.Genes Dev. 2003; 17: 214-228Crossref PubMed Scopus (121) Google Scholar). Early in mouse development migrating melanoblasts localize to the dermis and epidermis (Fitch et al., 2003Fitch K.R. McGowan K.A. van Raamsdonk C.D. et al.Genetics of dark skin in mice.Genes Dev. 2003; 17: 214-228Crossref PubMed Scopus (121) Google Scholar). Previously described mutations in Gnaq (GnaqMhdadsk1 and GnaqMhdadsk10) cause increases in the number of differentiated melanoblasts resulting in increased pigmentation in the dermis of mutant mice (Fitch et al., 2003Fitch K.R. McGowan K.A. van Raamsdonk C.D. et al.Genetics of dark skin in mice.Genes Dev. 2003; 17: 214-228Crossref PubMed Scopus (121) Google Scholar). Although GnaqM1J is similar to the previous mutations, in that increased dermal pigmentation is observed in adult mice, unlike the previous mutants, it results in both dermal and epidermal hyperpigmentation in tail skin. In light of these mutations, we hypothesize that the genes highlighted in Supplementary Figures 1 and 2 work in a coordinate manner to direct development, localization, and differentiation of skin melanoblasts. Studies using hairless mice with various degrees of cutaneous pigmentation suggested that pigment may play a role in barrier function (Man et al., 2014Man M.Q. Lin T.K. Santiago J.L. et al.Basis for enhanced barrier function of pigmented skin.J Invest Dermatol. 2014; 134: 2399-2407Abstract Full Text Full Text PDF PubMed Scopus (47) Google Scholar). As such, mutations in genes regulating skin pigmentation may seriously affect the function of the skin. Gnaq can be tied to barrier formations by way of its interactions with other barrier genes, like Cav1 (Supplementary Figure 2). Mutations affecting skin color are infrequent in the mice, because most affect hair color (Dadras et al., 2014Dadras S. Silva K.A. King L.E. et al.Transplantable malignant melanoma in LT.B6 congenic mice resembling pigmented epitheliod melanocytoma in humans.J Invest Dermatol. 2014; 134: 1772-1775Abstract Full Text Full Text PDF PubMed Scopus (2) Google Scholar, Sundberg and Silva, 2012Sundberg J.P. Silva K.A. What color is the skin of a mouse?.Vet Pathol. 2012; 49: 142-145Crossref PubMed Scopus (16) Google Scholar). Having single gene mutations on the inbred and very commonly used C57BL/6J background provides a new tool for refined evaluation of pigment in the skin of mice. C. Herbert Pratt: http://orcid.org/0000-0002-4964-8292 The authors state no conflict of interest. The authors thank Jesse Hammer for his technical assistance in preparing the figures. Research reported in this publication was supported by the National Institutes of Health (R01AR063781 to JPS; CHP, LD, and HF supported by P40 OD010972). The Jackson Laboratory Shared Scientific Services were supported in part by a Basic Cancer Center Core Grant from the National Cancer Institute (CA34196). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. Download .pdf (1.0 MB) Help with pdf files Supplementary Figures 1 and 2

BACKGROUND:Several technologies have been developed to aid dermatologists in the detection of melanoma in vivo including dermoscopy, multispectral digital skin lesion analysis (MDSLA), and reflectance confocal microscopy (RCM). To our knowledge, there have been no studies directly comparing MDSLA and RCM.OBJECTIVE:We conducted a repeated measures analysis comparing the sensitivity and specificity of MDSLA and RCM in the detection of melanoma (n = 55 lesions from 36 patients).METHODS:Study patients (n = 36) with atypical-appearing pigmented lesions (n = 55) underwent imaging by both RCM and MDSLA. Lesions were biopsied and analyzed by histopathology.RESULTS:RCM exhibited superior test metrics (P = .001, McNemar test) compared with MDSLA. Respectively, sensitivity measures were 85.7% and 71.4%, and specificity rates were 66.7% and 25.0%.LIMITATIONS:The sample size was relatively small and was collected from only one dermatologist's patient base; there was some degree of dermatopathologist interobserver variability; and only one confocalist performed the RCM image evaluations.CONCLUSION:RCM is a useful adjunct during clinical assessment of in vivo lesions suspicious for melanoma or those requiring re-excision because of high level of dysplasia or having features consistent with an atypical melanocytic nevus with severe cytologic atypia.

Technology now exists for rapid screening of mutated laboratory mice to identify phenotypes associated with specific genetic mutations. Large repositories exist for spontaneous mutants and those induced by chemical mutagenesis, many of which have never been fully studied or comprehensively evaluated. To supplement these resources, a variety of techniques have been consolidated in an international effort to create mutations in all known protein coding genes in the mouse. With targeted embryonic stem cell lines now available for almost all protein coding genes and more recently CRISPR/Cas9 technology, large-scale efforts are underway to create further novel mutant mouse strains and to characterize their phenotypes. However, accurate diagnosis of skin, hair, and nail diseases still relies on careful gross and histological analysis, and while not automated to the level of the physiological phenotyping, histopathology still provides the most direct and accurate diagnosis and correlation with human diseases. As a result of these efforts, many new mouse dermatological disease models are being characterized and developed.