Proliferating inverted follicular keratosis of genital skin: Case series of a challenging variant

BACKGROUND

Inverted follicular keratosis (IFK) is a benign cutaneous epithelial tumor typically presenting as a small papule on the head and neck. We have encountered deep endophytic tumors on genital skin with some characteristics of IFK but also atypical features, raising concern for squamous cell carcinoma (SCC).

METHODS

Four such tumors were identified in our database. Histopathologic analysis and ancillary studies were performed.

RESULTS

All patients were young women who presented with a solitary 0.5-1.0 cm lesion on the vulva, perineum, or inner buttock. Each showed a squamous proliferation arising from the epidermis, with endophytic growth that was deep and bulbous but not infiltrative. The tumor lobules contained eosinophilic keratinocytes, forming numerous squamous eddies. Small irregular spaces and dyskeratotic cells were frequently found. Nuclear pleomorphism was minimal to absent. All demonstrated wild-type p53 expression and lack of p16 block positivity. In situ hybridizations for human papillomavirus were negative. None of the three cases with follow-up data showed evidence of recurrence.

CONCLUSIONS

The absence of infiltrative growth or significant pleomorphism, the presence of numerous squamous eddies, the reassuring immunoprofile, and the lack of evidence of recurrence support a variant of IFK and speak against SCC. We propose the term "proliferating IFK" to highlight the florid squamous proliferation. Recognition of this unusual variant would avoid overdiagnosis of SCC.

Utility of GLI1 RNA Chromogenic in Situ Hybridization in Distinguishing Basal Cell Carcinoma From Histopathologic Mimics

Basal cell carcinoma (BCC) is the most common human malignancy and is a leading cause of nonmelanoma skin cancer-related morbidity. BCC has several histologic mimics which may have treatment and prognostic implications. Furthermore, BCC may show alternative differentiation toward a variety of cutaneous structures. The vast majority of BCCs harbor mutations in the hedgehog signaling pathway, resulting in increased expression of the GLI family of transcription factors. GLI1 immunohistochemistry has been shown to discriminate between several tumor types but demonstrates high background signal and lack of specificity. In this study, we evaluated the utility of GLI1 RNA chromogenic in situ hybridization (CISH) as a novel method of distinguishing between BCC and other epithelial neoplasms. Expression of GLI1 by RNA CISH was retrospectively evaluated in a total of 220 cases, including 60 BCCs, 37 squamous cell carcinomas (SCCs) including conventional, basaloid, and human papillomavirus infection (HPV)-associated tumors, 16 sebaceous neoplasms, 10 Merkel cell carcinomas, 58 benign follicular tumors, and 39 ductal tumors. The threshold for positivity was determined to be greater than or equal to 3 GLI1 signals in at least 50% of tumor cells. Positive GLI1 expression was identified in 57/60 BCCs, including metastatic BCC, collision lesions with SCC, and BCCs with squamous, ductal, or clear cell differentiation or with other unusual features compared to 1/37 SCCs, 0/11 sebaceous carcinomas, 0/5 sebaceomas, 1/10 Merkel cell carcinomas, 0/39 ductal tumors, and 28/58 follicular tumors. With careful evaluation, GLI1 RNA CISH is highly sensitive (95%) and specific (98%) in distinguishing between BCC and nonfollicular epithelial neoplasms. However, GLI1 CISH is not specific for distinguishing BCC from most benign follicular tumors. Overall, detection of GLI1 RNA by CISH may be a useful tool for precise classification of histologically challenging basaloid tumors, particularly in the setting of small biopsy specimens, metaplastic differentiation, or metastatic disease.

CD30 expression in cutaneous B-cell lymphomas

INTRODUCTION

CD30 expression has been infrequently described in cutaneous B-cell lymphomas (CBCLs). We examined CD30 expression in reactive lymphoid hyperplasia (RLH) and CBCL and correlated expression with clinicopathologic features.

METHODS

CD30 was examined in 82 CBCL patients and 10 RLH patients that had been evaluated in our cutaneous lymphoma clinics. The CBCL patients included: primary cutaneous follicle center lymphoma (PCFCL), Grade 1/2 systemic/nodal follicular lymphoma (SFL); primary cutaneous marginal zone lymphoma/lymphoproliferative disorder (PCMZL/LPD); systemic marginal zone lymphoma (SMZL); primary cutaneous diffuse large B-cell lymphoma, leg type (PCDLBCL-LT); and extracutaneous/systemic diffuse large B-cell lymphoma (eDLBCL). We scored CD30 expression for intensity and extent and related CD30 expression to age at first diagnosis, sex, site of biopsy, clinical appearance, extracutaneous involvement, multiple cutaneous lesions, B-symptoms, lymphadenopathy, positive positron emission tomography/computed tomography (PET/CT), elevated lactate dehydrogenase (LDH), and positive bone marrow biopsy.

RESULTS

CD30 expression was identified in 35% of CBCL, ranging from few, weak, scattered cells to strong and diffuse expression. It was most common in PCFCL and was not expressed in PCDLBCL-LT. Rare PCFCL expressed strong, diffuse CD30. Some cases of PCMZL/LPD, SMZL, FL, and RLH showed scattered, strongly positive cells. CD30 expression in CBCL was associated with favorable clinical features: younger age, negative PET/CT, and an LDH within normal limits.

CONCLUSIONS

CD30 may be expressed in CBCL, possibly causing diagnostic confusion. CD30 expression was most commonly identified in PCFCL and is associated with favorable clinical features. In cases with strong and diffuse expression, CD30 could be a therapeutic target.

Unusual drug reaction with features of colchicine toxicity in a patient on colchicine and allopurinol

A 58-year-old woman was admitted for heart failure and concern for cardiogenic shock. The patient had been recently placed on colchicine and allopurinol, 4 months and 3 weeks, respectively, prior to admission. Upon admission, she had a cutaneous eruption that had started abruptly several days after allopurinol initiation. It included multiple erythematous papules with scant scale on the forearms and numerous erythematous papules on the legs. Because of the varied morphologic presentation, biopsies from both the thigh and forearm were performed for a suspected drug reaction. The specimen from the thigh showed a superficial-dermal, band-like lymphocytic infiltrate with dyskeratosis and numerous intraepidermal mitotic figures predominantly in metaphase. In addition, there were neutrophils with leukocytoclasia. The specimen from the forearm showed superficial perivascular lymphocytic inflammation and intraepidermal dyskeratosis with mitotic figures similar to the thigh biopsy specimen but without a dermal neutrophilic infiltrate. An unusual drug eruption with features of colchicine toxicity was favored. Colchicine toxicity is not a commonly encountered clinical scenario and cutaneous findings have only rarely been described. Herein we report an exceedingly rare case of an unusual drug reaction with "colchicine figures" (i.e., ring-shaped mitotic figures arrested in metaphase) consistent with colchicine toxicity.

Spindle Cell/Pleomorphic Lipoma With Trichodiscoma-like Epithelial Hyperplasia Mimicking Atypical Fibroxanthoma/Pleomorphic Dermal Sarcoma

ABSTRACT

A 58-year-old man presented with a lesion on the nose suspicious for basal cell carcinoma. An initial biopsy specimen reviewed at an outside institution showed a cytologically atypical spindle cell proliferation that lacked expression of cytokeratins or melanocytic markers. The resulting differential diagnosis included atypical fibroxanthoma and pleomorphic dermal sarcoma. Histopathologic examination of the excision specimen at our institution revealed an intradermal pleomorphic and spindle cell tumor which extended into underlying skeletal muscle. The tumor was associated with a fibromyxoid stroma, scattered adipocytes, and hyperplastic folliculosebaceous epithelium at the periphery. The pleomorphic tumor cells showed hyperchromatic nuclei with smudgy chromatin, and no mitotic activity was detected. Overall, the cellularity was less than would be expected for atypical fibroxanthoma/pleomorphic dermal sarcoma. Furthermore, the tumor cells were strongly positive for CD34 and showed diffuse loss of retinoblastoma protein by immunohistochemistry. Consequently, a diagnosis of benign CD34-positive pleomorphic spindle cell tumor was rendered, with features overlapping between spindle cell/pleomorphic lipoma and trichodiscoma. Subsequent single-nucleotide pleomorphism array testing revealed heterozygous loss of chromosome 13q in a region that spanned the RB1 locus and copy number loss at 16q, favoring that the proliferation in fact represents a spindle cell/pleomorphic lipoma with trichodiscoma-like epithelial induction. This case highlights an important diagnostic pitfall that may be avoided by recognizing characteristic architectural and cytologic features of this spectrum of lesions.

The deacylase SIRT5 supports melanoma viability by influencing chromatin dynamics

Cutaneous melanoma remains the most lethal skin cancer, and ranks third among all malignancies in terms of years of life lost. Despite the advent of immune checkpoint and targeted therapies, only roughly half of patients with advanced melanoma achieve a durable remission. Sirtuin 5 (SIRT5) is a member of the sirtuin family of protein deacylases that regulates metabolism and other biological processes. Germline Sirt5 deficiency is associated with mild phenotypes in mice. Here we showed that SIRT5 was required for proliferation and survival across all cutaneous melanoma genotypes tested, as well as uveal melanoma, a genetically distinct melanoma subtype that arises in the eye and is incurable once metastatic. Likewise, SIRT5 was required for efficient tumor formation by melanoma xenografts and in an autochthonous mouse Braf Pten-driven melanoma model. Via metabolite and transcriptomic analyses, we found that SIRT5 was required to maintain histone acetylation and methylation levels in melanoma cells, thereby promoting proper gene expression. SIRT5-dependent genes notably included MITF, a key lineage-specific survival oncogene in melanoma, and the c-MYC proto-oncogene. SIRT5 may represent a druggable genotype-independent addiction in melanoma.

Primary cutaneous malignant perivascular epithelioid cell tumor: Case of a rare tumor with review of the literature

Perivascular epithelioid cell tumors (PEComas) are mesenchymal neoplasms with characteristic epithelioid or spindled cytomorphology that typically grow around blood vessels. These tumors are phenotypically and immunohistochemically distinct, expressing markers of both melanocytic and smooth muscle differentiation. Herein, we describe a case of histopathologically malignant cutaneous PEComa without metastatic spread, with review of the pertinent literature. Telescoping punch biopsy demonstrated an epithelioid neoplasm with marked atypia, hypercellularity, and increased mitotic activity. Immunohistochemical stains for HMB-45, NK1-C3, PGP9.5, MiTF, CD10, and CD68 were positive within tumor cells. In addition, there was diffuse expression of caldesmon and focal cytoplasmic staining for smooth muscle actin on the excision specimen. The patient underwent treatment with surgical excision with adjuvant radiation and surveillance computed tomography (CT). The patient remains free of recurrence or metastatic disease after 10 months of follow-up. To our knowledge, this is only the third reported case of a malignant cutaneous PEComa reported in the literature to date.

Immunophenotypic switch in cutaneous T-cell lymphoma: A series of three cases and review of the literature

Primary cutaneous T-cell lymphoma (CTCL) comprises a heterogeneous group of neoplasms with variable clinical behavior. Immunophenotypic switch (IS) is a phenomenon that occurs during lymphoma progression and is defined by an alteration in the immunophenotypic expression of a tumor with retention of its genotypic signature. This has been well-recognized in hematopoietic neoplasms; however, it has been rarely reported in CTCL and its clinical implications are not well understood. We present the clinical, histopathologic, immunophenotypic, and genetic findings of three cases of CTCL that demonstrated IS post treatment with variable outcomes. We add our cases to the small number previously reported to increase awareness of this phenomenon and its diagnostic challenge.

Virus-positive Merkel Cell Carcinoma Is an Independent Prognostic Group with Distinct Predictive Biomarkers

PURPOSE

Merkel cell carcinoma (MCC) is an aggressive cutaneous neuroendocrine carcinoma that can be divided into two classes: virus-positive (VP) MCC, associated with oncogenic Merkel cell polyomavirus (MCPyV); and virus-negative (VN) MCC, associated with photodamage.

EXPERIMENTAL DESIGN

We classified 346 MCC tumors from 300 patients for MCPyV using a combination of IHC, ISH, and qPCR assays. In a subset of tumors, we profiled mutation status and expression of cancer-relevant genes. MCPyV and molecular profiling results were correlated with disease-specific outcomes. Potential prognostic biomarkers were further validated by IHC.

RESULTS

A total of 177 tumors were classified as VP-MCC, 151 tumors were VN-MCC, and 17 tumors were indeterminate. MCPyV positivity in primary tumors was associated with longer disease-specific and recurrence-free survival in univariate analysis, and in multivariate analysis incorporating age, sex, immune status, and stage at presentation. Prioritized oncogene or tumor suppressor mutations were frequent in VN-MCC but rare in VP-MCC. TP53 mutation developed with recurrence in one VP-MCC case. Importantly, for the first time we find that VP-MCC and VN-MCC display distinct sets of prognostic molecular biomarkers. For VP-MCC, shorter survival was associated with decreased expression of immune markers including granzyme and IDO1. For VN-MCC, shorter survival correlated with high expression of several genes including UBE2C.

CONCLUSIONS

MCPyV status is an independent prognostic factor for MCC. Features of the tumor genome, transcriptome, and microenvironment may modify prognosis in a manner specific to viral status. MCPyV status has clinicopathologic significance and allows for identification of additional prognostic subgroups.

Ethical and professionalism issues in dermatopathology: A cross-sectional survey of American Society of Dermatopathology Members

BACKGROUND

Data regarding ethical/professional issues affecting dermatopathologists are lacking despite their importance in establishing policy priorities and educational content for dermatopathology.

METHODS

A 14-item cross-sectional survey about ethical/professional issues in dermatopathology was distributed over e-mail to members of the American Society of Dermatopathology from June to September 2019.

RESULTS

Two hundred sixteen surveys were completed, with a response rate of 15.3%. Respondents ranked appropriate and fair utilization of healthcare resources (n = 83 or 38.6%) as the most often encountered ethical/professional issue. Conflict of interest was ranked as the most urgent or important ethical/professional issue (n = 83 or 39.3%). One hundred thirty-three (61.6%) respondents felt "somewhat" or "not at all" well equipped to handle ethical dilemmas in practice and 47 (22.8%) respondents identified a major or extreme burden (eg, have considered resigning/retiring) due to ethical challenges.

CONCLUSIONS

Areas of priority in ethics and professionalism issues can guide future policy and educational content in dermatopathology.

Cutaneous follicle center lymphomas with plasmacytic differentiation

Follicle center lymphomas, including primary cutaneous follicle center lymphoma (PCFCL), may rarely show plasmacytic differentiation. Such cases can pose a diagnostic challenge and can be mistaken for other lymphomas that more commonly include plasma cells. Here, we report four cases of PCFCL and one case of systemic follicular lymphoma involving the skin with associated monotypic plasma cells, including the clinical, morphologic and immunophenotypic features.

Cutaneous microsporidiosis in an immunosuppressed patient

Microsporidia are a group of obligate intracellular parasites that naturally infect domestic and wild animals. Human microsporidiosis is an increasingly recognized multisystem opportunistic infection. The clinical manifestations are diverse with diarrhea being the most common presenting symptom. We present a 52-year-old woman with a history of amyopathic dermatomyositis complicated by interstitial lung disease managed with mycophenolate mofetil and hydroxychloroquine who presented with a 7-month history of recurrent subcutaneous nodules as well as intermittent diarrhea and chronic sinusitis. A punch biopsy showed superficial and deep lymphocytic and granulomatous dermatitis with focal necrosis. Tissue stains for microorganisms revealed oval 1 to 3 μm spores within the necrotic areas in multiple tissue stains. Additional studies at the Centers for Disease Control and Prevention confirmed cutaneous microsporidiosis. This case is one of very few confirmed examples of cutaneous microsporidiosis reported in the literature.

Cross-species genomic landscape comparison of human mucosal melanoma with canine oral and equine melanoma

Mucosal melanoma is a rare and poorly characterized subtype of human melanoma. Here we perform a cross-species analysis by sequencing tumor-germline pairs from 46 primary human muscosal, 65 primary canine oral and 28 primary equine melanoma cases from mucosal sites. Analysis of these data reveals recurrently mutated driver genes shared between species such as NRAS, FAT4, PTPRJ, TP53 and PTEN, and pathogenic germline alleles of BRCA1, BRCA2 and TP53. We identify a UV mutation signature in a small number of samples, including human cases from the lip and nasal mucosa. A cross-species comparative analysis of recurrent copy number alterations identifies several candidate drivers including MDM2, B2M, KNSTRN and BUB1B. Comparison of somatic mutations in recurrences and metastases to those in the primary tumor suggests pervasive intra-tumor heterogeneity. Collectively, these studies suggest a convergence of some genetic changes in mucosal melanomas between species but also distinctly different paths to tumorigenesis.

Merkel cell carcinoma arising in association with cutaneous T-cell lymphoma: A potential diagnostic pitfall

Merkel cell carcinoma (MCC) is a rare, aggressive cutaneous neuroendocrine carcinoma with increased prevalence in patients with immunosuppression or B-cell neoplasms. To the best of our knowledge, an association with cutaneous T-cell lymphoma (CTCL) has not been previously described. In this report, we present two cases of MCC arising in the setting of CTCL. The first case was a female during her 70s with previously diagnosed stage IVA1 Sezary syndrome. Biopsy of a scaly patch showed two distinct abnormal cell populations. The first population consisted of hyperchromatic dermal and epidermotropic lymphocytes, expressing CD3 and CD4 with diminished CD7. The second population consisted of intraepidermal clusters of larger atypical cells that expressed synaptophysin, neurofilament, CK20, and Merkel cell polyomavirus transcript. The combination of findings was consistent with intraepidermal MCC in a background of CTCL. Excision showed residual intraepidermal MCC without dermal involvement. The second case was a male during his 50s with a longstanding history of mycosis fungoides, who presented with a new lesion on his right thigh. Biopsy and excision showed dermal MCC without secondary involvement by CTCL. Our cases show that MCC may rarely occur in the setting of T-cell lymphoma, and that intraepidermal MCC may mimic epidermotropic T-cells.

Molecular testing of borderline cutaneous melanocytic lesions: SNP array is more sensitive and specific than FISH

Melanocytic lesions with borderline features are diagnostically challenging. Single-nucleotide polymorphism (SNP) arrays, which detect genomic copy number alterations (CNAs), can be helpful in distinguishing between nevi and melanoma. Fluorescence in situ hybridization (FISH) has been used as a more rapid, less expensive alternative to SNP array, using a panel of probes that are often gained or lost in melanoma. We used SNP array data from 63 borderline cutaneous melanocytic lesions and 44 definitive melanomas to predict the performance of FISH testing. Lesions were considered positive by "virtual FISH" if 1 or more of the 5 FISH-probed loci demonstrated appropriate CNAs by SNP array. Cases were classified as positive by SNP array if ≥3 CNAs were present, based on internal validation studies, or if FISH criteria were met. Conventional FISH was performed in 33 cases (17 borderline lesions, 16 melanomas). Of the 63 borderline cases, 44 (70%) were positive by SNP array and 30 (48%) were positive by virtual FISH. A higher proportion of melanomas were positive by SNP array (41/44, 93% sensitivity) and virtual FISH (36/44, 82% sensitivity). Virtual FISH had 61% sensitivity in the borderline group using SNP array as the gold standard, whereas specificity was 84%. There was good correlation between conventional and virtual FISH, with agreement in 30 of 33 (91%) cases. Although FISH is highly effective in distinguishing between nevi and melanoma in cases where the histological diagnosis is straightforward, it is not nearly as sensitive or specific as SNP array when applied to borderline lesions.

Neurofilament is superior to cytokeratin 20 in supporting cutaneous origin for neuroendocrine carcinoma

AIM

Primary cutaneous neuroendocrine carcinoma, or Merkel cell carcinoma (MCC), cannot be distinguished morphologically from small-cell neuroendocrine carcinomas (SmCC) from other sites. Immunohistochemistry is required to confirm cutaneous origin, and is also used for detection of sentinel lymph node (SLN) metastases of MCC. Cytokeratin 20 (CK20) expression is commonly used for these purposes, but is negative in some MCC cases, and has unclear specificity. We evaluated immunohistochemistry for neurofilament and CK20 in MCC compared with SmCC from other sites.

METHODS AND RESULTS

We evaluated neurofilament expression in 55 MCC specimens from 39 unique patients, including nine CK20-negative MCC tumours. Neurofilament expression was observed in 42 of 55 (76.4%) MCC cases, including seven of nine (77.8%) CK20-negative MCC cases. Neurofilament was expressed in nine of 12 (75%) Merkel cell polyomavirus-positive tumours and five of 10 (50%) virus-negative tumours. Compared to a standard immunohistochemical panel (cytokeratin cocktail and CK20), neurofilament was 87.5% sensitive for detecting SLN metastases. Neurofilament and CK20 expression was also assessed in 61 extracutaneous SmCC from 60 unique patients, with primary sites including lung (27), bladder (18), cervix (3), gastrointestinal tract (3), sinonasal tract (2) and other sites (7). The specificity of neurofilament and CK20 for MCC versus non-cutaneous SmCC was 96.7% and 59.0%, respectively.

CONCLUSIONS

Neurofilament has superior specificity to CK20 in distinguishing MCC from non-cutaneous SmCC. Neurofilament is frequently expressed in CK20- and virus-negative MCC tumours. Limitations of neurofilament immunohistochemistry include lower sensitivity than CK20 and subtle staining in some tumours. However, our findings indicate that neurofilament is useful for excluding non-cutaneous SmCC.

Activation of cancer-associated fibroblasts is required for tumor neovascularization in a murine model of melanoma

Metastatic melanoma is highly fatal. Within the tumor microenvironment, the role of cancer-associated fibroblasts (CAFs) in melanoma metastasis and progression is relatively understudied. The matricellular protein CCN2 (formerly termed connective tissue growth factor, CTGF) is overexpressed, in a fashion independent of BRAF mutational status, by CAFs in melanoma. Herein, we find, in human melanoma patients, that CCN2 expression negatively correlates with survival and positively correlates with expression of neovascularization markers. To assess the role of CAFs in melanoma progression, we used C57BL/6 mice expressing a tamoxifen-dependent cre recombinase expressed under the control of a fibroblast-specific promoter/enhancer (COL1A2) to delete CCN2 postnatally in fibroblasts. Mice deleted or not for CCN2 in fibroblasts were injected subcutaneously with B16-F10 melanoma cells. Loss of CCN2 in CAFs resulted in reduced CAF activation, as detected by staining with anti-α-smooth muscle actin antibodies, and reduced tumor-induced neovascularization, as detected by micro-computed tomography (micro-CT) and staining with anti-CD31 antibodies. CCN2-deficient B16(F10) cells were defective in a tubule formation/vasculogenic mimicry assay in vitro. Mice deleted for CCN2 in CAFs also showed impaired vasculogenic mimicry of subcutaneously-injected B16-F10 cells in vivo. Our results provide new insights into the cross-talk among different cell types in the tumor microenvironment and suggest CAFs play a heretofore unappreciated role by being essential for tumor neovascularization via the production of CCN2. Our data are consistent with the hypothesis that activated CAFs are essential for melanoma metastasis and that, due to its role in this process, CCN2 is a therapeutic target for melanoma.

Malignant melanoma with osteosarcomatous differentiation in a lymph node metastasis

Osteocartilaginous differentiation in malignant melanoma is rare and can pose a diagnostic challenge. In previously reported cases, melanomas were predominantly located on acral and mucosal sites, with osteocartilaginous differentiation present in either primary or recurrent lesions. We report a case of a 52-year-old female with malignant melanoma located on the right upper back exhibiting osteosarcomatous differentiation only in the axillary lymph node metastasis. This case serves to highlight that the divergent differentiation can occur in lymph node metastases while being absent in the primary lesion. The patient's medical history, careful histological examination, and immunohistochemistry may be necessary for establishing the correct diagnosis.

Comprehensive histopathological comparison of epidermotropic/dermal metastatic melanoma and primary nodular melanoma

AIMS

Metastatic melanoma involving the epidermis and/or upper dermis may show significant histological overlap with primary cutaneous melanoma, especially the nodular subtype. Proper histopathological classification is crucial to appropriate staging and management, but is often challenging. The aim of this study was to identify helpful histopathological features for differentiating epidermotropic/dermal metastatic melanoma (EDMM) and primary nodular melanoma (PNM).

METHODS AND RESULTS

A cohort of EDMMs (n = 74) and PNMs (n = 75) was retrospectively reviewed for various histopathological features, and the data were compared between groups by the use of univariate analysis. Features significantly associated with EDMM included a tumour size of <2 mm, an absence of tumour-infiltrating lymphocytes and plasma cells, monomorphism, and involvement of adnexal epithelium. Features associated with PNM included a polypoid (exophytic) configuration, prominent tumour-infiltrating plasma cells (TIPs), a tumour size of >10 mm, ulceration, epidermal collarettes, a higher mitotic rate, necrosis, multiple phenotypes, significant pleomorphism, and lichenoid inflammation. In multivariate analysis, a logistic regression model including large tumour size, ulceration, prominent TIPs, lichenoid inflammation and epidermal collarettes was highly predictive of PNM. Six (8%) EDMMs from three patients showed an 'epidermal-only' or 'epidermal-predominant' pattern closely simulating in-situ or microinvasive melanoma. Two of these cases were tested by fluorescence in-situ hybridisation, which confirmed clonal relationships with their corresponding primary melanomas.

CONCLUSIONS

This is the first comprehensive histopathological comparison of EDMM and PNM. Recognition of the above histopathological associations should aid in the correct classification and staging of cutaneous melanoma. Epidermotropic metastatic melanomas may occasionally show an epidermal-only/epidermal-predominant pattern; accurate diagnosis requires prudent clinical correlation and, when necessary, ancillary molecular tests.

Gynecologic melanomas: A clinicopathologic and molecular analysis

OBJECTIVE

Melanoma originating from gynecologic sites (MOGS), including the vulva, vagina, and cervix, is a rare and aggressive form of melanoma with poor long-term clinical outcome. The clinicopathologic features of vulvar and non-vulvar tumors remain relatively understudied, and in contrast to cutaneous melanomas at non-sun-exposed sites, MOGS typically do not harbor BRAF mutations. Thus, we sought to analyze the clinicopathologic and molecular features of MOGS.

METHODS

A large retrospective cohort of patients with MOGS (n=59) at a single large academic institution over a 28-year period was identified. Associations among clinicopathologic characteristics were assessed via standard statistical approaches, and clinical outcome was examined using Cox regression analysis. Sanger sequencing was utilized to identify mutations in hotspot regions of BRAF, KIT, NRAS, and CTNNB1.

RESULTS

Tumors involving the vagina and/or cervix (non-vulvar) are significantly associated with high-risk clinicopathologic features, including increased tumor thickness, ulceration, positive resection margins, lymph node metastasis, and poor long-term clinical outcome (with increased risk of death due to disease). The aggressive clinical behavior of non-vulvar tumors is independent of advanced clinical stage and lymph node metastasis in multivariate analysis. Targeted molecular analysis confirms an overall low rate of oncogenic mutations in our MOGS cohort, although KIT mutations (particularly in exon 11) are relatively enriched.

CONCLUSIONS

Overall, our results show that non-vulvar MOGS are aggressive tumors with poor long-term clinical outcome and indicate that few targeted therapeutic options are currently available to patients with MOGS.

Increased expression of EZH2 in Merkel cell carcinoma is associated with disease progression and poorer prognosis

Enhancer of zeste homolog 2 (EZH2) is a histone methyltransferase that affects tumorigenesis by epigenetic gene silencing. Merkel cell carcinoma (MCC) is a rare cutaneous neuroendocrine carcinoma that has a high risk of disease progression with nodal and distant metastases. Here, we evaluated EZH2 expression by immunohistochemistry in a cohort of 85 MCC tumors (29 primary tumors, 41 lymph node metastases, 13 in-transit metastases, and 2 distant metastases) with clinical follow-up. We show strong/moderate EZH2 expression in 54% of tumors. Importantly, weak expression of EZH2 in the primary tumor, but not nodal metastases, correlated with improved prognosis compared to moderate/strong EZH2 expression (5-year MCC-specific survival of 68% versus 22%, respectively, P=.024). In addition, EZH2 was expressed at higher levels in nodal metastases compared to primary tumors (P=.005). Our data demonstrate that EZH2 has prognostic value and may play an oncogenic role in MCC.

Molecular Profiling of Multiple Primary Merkel Cell Carcinoma to Distinguish Genetically Distinct Tumors From Clonally Related Metastases

Importance

Merkel cell carcinoma (MCC) is an aggressive cutaneous neuroendocrine carcinoma. In rare cases, the development of an additional cutaneous MCC tumor is clinically consistent with a second primary MCC tumor rather than a cutaneous metastasis, which has important treatment and prognostic implications.

Objective

To evaluate genetic relatedness in 4 cases with the clinical diagnosis of multiple primary MCCs.

Design, Setting, and Participants

In this case series, 7 cases of clinically designated multiple primary MCC were identified; 4 cases met inclusion criteria for next-generation sequencing (NGS) analysis. Mutations, copy number alterations, and Merkel cell polyomavirus (MCPyV) sequence were analyzed and compared between clinically designated multiple primary tumors to characterize genetic relatedness and hence assess clonality. Patients with clinically designated multiple primary MCC were identified from the multidisciplinary MCC Program at the University of Michigan, a tertiary care center.

Main Outcomes and Measures

Four cases of clinically designated multiple primary MCC were characterized by tumor sequencing and targeted MCPyV sequencing to distinguish independent primary tumors from related metastases.

Results

Overall, 4 patients in their 70s or 80s were included and analyzed. Cases 1 and 4 were verified as genetically distinct primary tumors and did not harbor similar copy number alterations or demonstrate significant mutational overlap. Cases 2 and 3 were designated as clonally related based on overlapping copy number alterations. In clonally related tumors, chromosomal copy number changes were more reliable than mutations for demonstrating clonality. Regardless of clonality, we found that MCPyV status was concordant for all tumor pairs and MCPyV positive tumors harbored predominatly subclonal mutations.

Conclusions and Relevance

Our findings suggest that patients with MCC may develop a second genetically distinct primary tumor; in this case, the subsequent tumor is likely to develop through similar mechanisms of pathogenesis, either MCPyV-mediated or ultraviolet light-mediated. Next-generation sequencing analysis of chromosomal copy number changes and mutations is useful in distinguishing multiple primary MCCs from progression of MCC clinically resembling multiple primaries, allowing appropriate staging of the patient.

Recurrence and Survival in Patients With Merkel Cell Carcinoma Undergoing Surgery Without Adjuvant Radiation Therapy to the Primary Site

IMPORTANCE

The use of adjuvant radiation therapy (RT) to the primary site in Merkel cell carcinoma (MCC) is not uncommon. However, the need for adjuvant RT to the primary site in patients at low risk for local recurrence is questionable.

OBJECTIVES

To examine the occurrence of true local, satellite, in-transit, regional, and distant recurrences in patients undergoing surgery alone without adjuvant RT to the primary site. To establish overall survival (OS), MCC-specific survival (MCCSS), and disease-free survival (DFS) relationships in a cohort of patients with MCC.

DESIGN, SETTING, AND PARTICIPANTS

Our University of Michigan Multidisciplinary MCC Program database was used to obtain characteristics and outcome measures for 104 patients (105 primary MCCs) with tumors less than 2 cm in diameter. The majority of patients were treated between July 2006 and November 2012.

MAIN OUTCOMES AND MEASURES

Outcome measures included the occurrence of true local, satellite, in-transit, regional, and distant recurrences. End points included OS, MCCSS, and DFS.

RESULTS

Overall, information for 55 men and 49 women with 105 primary MCCs was obtained; 19 patients developed recurrent disease, and the mean time to first recurrence was 10.7 months. True local recurrence occurred in 1 patient with concurrent in-transit recurrence. Satellite recurrence occurred in 1 patient with concurrent regional recurrence. Four additional patients developed in-transit metastases. Thirteen patients had a regional recurrence component, 4 patients had distant metastases, and 6 patients developed subsequent regional and/or distant recurrences. Stratified by initial pathologic stage, the OS and MCCSS at 48 months were estimated to be 85.0% (95% CI, 71.8%-92.3%) and 94.4% (95% CI, 83.4%-98.2%) for patients with stage 1A/B disease and 63.2% (95% CI, 36.6%-81.1%) and 78.1% (95% CI, 50.0%-91.5%) for patients with stage 3A disease. The OS and MCCSS at 24 months for patients with stage 3B disease were both 50.0% (95% CI, 5.8%-84.5%).

CONCLUSIONS AND RELEVANCE

In selected MCC patients with primary tumors less than 2 cm in diameter treated with surgery alone without adjuvant RT to the primary site, we found a low occurrence of true local recurrences and satellite recurrences. This relatively low rate of local recurrence questions the need for adjuvant RT to the primary tumor site in patients with small low-risk lesions.

Superficial papular neuroma: Case series of a new entity

BACKGROUND

Dermal neural lesions arise in various circumstances and may be difficult to classify.

METHODS

We describe the clinical, histopathologic and immunophenotypic features of a series of terminally differentiated neural lesions not described previously, to our knowledge.

RESULTS

Four cases from men aged 58 to 66 years were included. Some lesions reportedly bled, but no inciting trauma or prior biopsies were reported. None recurred after biopsy, with follow-up ranging from 19 to 113 months. All lesions were papular, with vertically oriented S100-positive spindled cells and nerve fibers in the papillary dermis. Slight epidermal hyperplasia, dilated superficial thin-walled vessels and minimal to mild inflammation were seen in each. Fibers were uniformly fine in 3 cases, with slightly thicker central fibers in the fourth. Three had parakeratotic scale. None were associated with dermal fibrosis or adnexal proliferation. Neurofilament stained axons in each. EMA was negative in all cases. CD34, melan-A and HMB45 were negative when performed.

CONCLUSIONS

We report a small series of benign neural lesions and propose the name "superficial papular neuroma" for this distinct entity. Awareness is important to understand the clinical significance of these lesions and avoid misinterpretation that could lead to overtreatment, unnecessary work-up and increased cost.

Age and Gender Associations of Virus Positivity in Merkel Cell Carcinoma Characterized Using a Novel RNA In Situ Hybridization Assay

Purpose: Merkel cell carcinoma (MCC) is a highly aggressive neuroendocrine tumor of the skin. Merkel cell polyomavirus (MCPyV) plays an oncogenic role in the majority of MCCs. Detection of MCPyV in MCCs has diagnostic utility and prognostic potential. We investigated whether RNAscope, an RNA in situ hybridization (ISH) assay for detection of RNA transcripts in tissues, is useful for MCPyV detection.Experimental Design: We applied an RNAscope probe targeting MCPyV T antigen transcripts on tissue microarrays (TMA) and whole-tissue sections encompassing 87 MCCs from 75 patients, 14 carcinomas of other types, and benign tissues. For comparison, qPCR was performed on 57 cases of MCC from 52 patients.Results: RNA-ISH demonstrated the presence of MCPyV in 37 of 75 cases (49.3%). Notably, tumors from younger patients (<73 years) had a significantly higher virus positivity than those from elderly patients (≥73 years; 64.9% vs. 34.2%, P = 0.011). Female patients had a higher positive rate of MCPyV than male patients (66.7% vs. 39.6%, P = 0.032). Data from both RNA-ISH and qPCR were available for 57 samples. Considering MCPyV qPCR as the gold standard for determining MCPyV status, RNAscope had 100% sensitivity and 100% specificity. There was a strong correlation between qPCR copy number and RNA-ISH product score (Spearman correlation coefficient R² = 0.932, P < 0.0001).Conclusions: RNA-ISH is comparably sensitive to qPCR for detection of MCPyV and allows for correlation with tissue morphology. This study also reveals a significant association between age, gender, and MCPyV positivity. Clin Cancer Res; 23(18); 5622-30. ©2017 AACR.

Transcriptional dissection of melanoma identifies a high-risk subtype underlying TP53 family genes and epigenome deregulation

BACKGROUND

Melanoma is a heterogeneous malignancy. We set out to identify the molecular underpinnings of high-risk melanomas, those that are likely to progress rapidly, metastasize, and result in poor outcomes.

METHODS

We examined transcriptome changes from benign states to early-, intermediate-, and late-stage tumors using a set of 78 treatment-naive melanocytic tumors consisting of primary melanomas of the skin and benign melanocytic lesions. We utilized a next-generation sequencing platform that enabled a comprehensive analysis of protein-coding and -noncoding RNA transcripts.

RESULTS

Gene expression changes unequivocally discriminated between benign and malignant states, and a dual epigenetic and immune signature emerged defining this transition. To our knowledge, we discovered previously unrecognized melanoma subtypes. A high-risk primary melanoma subset was distinguished by a 122-epigenetic gene signature ("epigenetic" cluster) and TP53 family gene deregulation (TP53, TP63, and TP73). This subtype associated with poor overall survival and showed enrichment of cell cycle genes. Noncoding repetitive element transcripts (LINEs, SINEs, and ERVs) that can result in immunostimulatory signals recapitulating a state of "viral mimicry" were significantly repressed. The high-risk subtype and its poor predictive characteristics were validated in several independent cohorts. Additionally, primary melanomas distinguished by specific immune signatures ("immune" clusters) were identified.

CONCLUSION

The TP53 family of genes and genes regulating the epigenetic machinery demonstrate strong prognostic and biological relevance during progression of early disease. Gene expression profiling of protein-coding and -noncoding RNA transcripts may be a better predictor for disease course in melanoma. This study outlines the transcriptional interplay of the cancer cell's epigenome with the immune milieu with potential for future therapeutic targeting.

FUNDING

National Institutes of Health (CA154683, CA158557, CA177940, CA087497-13), Tisch Cancer Institute, Melanoma Research Foundation, the Dow Family Charitable Foundation, and the Icahn School of Medicine at Mount Sinai.

Protein gene product 9.5 (PGP9.5) expression in benign cutaneous mesenchymal, histiocytic, and melanocytic lesions: comparison with cellular neurothekeoma

Cellular neurothekeoma (CNTK) frequently enters the differential diagnosis of a benign dermal cellular proliferation. Diagnosis often relies on immunohistochemistry including the use of protein gene product 9.5 (PGP9.5). A previous study demonstrated PGP9.5 expression across a wide variety of soft tissue neoplasms. We explored the utility of this antibody in distinguishing CNTK from other benign dermal-based lesions. A cohort of CNTK (n=7) and benign cutaneous lesions of neural (n=28), fibrohistiocytic (n=23), fibroblastic (n=25), histiocytic (n=18), myofibroblastic (n=7), smooth muscle (n=14), and melanocytic (n=12) differentiations were immunostained with PGP9.5. Staining was graded by H-score and compared with CNTK. A significantly higher H-score was found in CNTK compared with the fibrohistiocytic (p=0.0001), histiocytic (p=0.0016), myofibroblastic (p=0.0003), smooth muscle (p<0.0001), and melanocytic (p=0.0004) groups, with the exceptions of plexiform fibrohistiocytic tumour, xanthoma, and xanthogranuloma. No significant difference was found when comparing CNTK with fibroblastic and neural lesions, with the exceptions of neurofibroma and perineurioma. In conclusion, PGP9.5 is helpful in distinguishing CNTK from most benign cutaneous fibrohistiocytic, histiocytic, myofibroblastic, smooth muscle, and melanocytic lesions. In addition to CNTK and neural lesions, PGP9.5 is also expressed in benign fibroblastic lesions, and therefore distinction of these lesions should not be based on PGP9.5 positivity.

Detection of Occult Invasion in Melanoma In Situ

Importance

It is unclear why some patients with in situ melanoma develop metastases. Few reports demonstrate occult invasion with immunohistochemistry staining, which were discordant with reports interpreting such staining as false-positive.

Objective

To investigate the occurrence of occult invasive disease within in situ melanoma by using methods to circumvent potential limitations in prior study designs.

Design, Setting, and Participants

Unequivocal in situ melanoma without associated nevi or regression was identified using a consecutive sample of 33 cases plus 1 index case in an academic medical center. After cutting deeper into the most representative tissue block, 3 sequential slides were stained with hematoxylin-eosin (H-E), melanoma antigen (melan-A), and again with H-E. Melan-A-stained slides showing definitive invasion were double-stained with Sry-related HMg-Box gene 10 (SOX10) to confirm the melanocytic nature of the cells of interest. The study evaluated the possibilities of occult invasion detected by immunohistochemistry, sectioning deeper into the tissue block, or both. Slides were independently scored by 3 dermatopathologists with interrater reliability assessed. The study was conducted from January 1, 2012, to July 31, 2014.

Main Outcomes and Measures

Assessment of the occurrence of occult invasion, diagnosis of invasion by immunohistochemistry alone vs cutting deeper into the tissue block, and occurrence of false-positive results using immunohistochemistry alone.

Results

Occult invasive melanoma was detected in 11 of 33 consecutive cases (33%) of previously diagnosed unequivocal in situ melanoma. Six of 11 melanomas (55%) were diagnosable only by immunohistochemistry. The remaining 5 tumors (45%) were diagnosable by both melan-A and H-E staining, likely as a result of simply cutting deeper into the tissue block. Four cases (12%) showed a few melan-A-positive cells in the dermis, which was insufficient for a diagnosis of invasive melanoma and most consistent on a cytomorphologic basis with occult nevi.

Conclusions and Relevance

Although rare, in situ melanoma may metastasize. Occult microinvasion was demonstrated in up to one-third of the specimens in the present study, which provides a plausible explanation for this adverse event. Thus, history and physical examination including regional lymph nodes, education, and surveillance recommendations should be based on a very low, but not zero, risk of metastasis.

Immunohistochemical evaluation of p16 expression in cutaneous histiocytic, fibrohistiocytic and undifferentiated lesions

BACKGROUND

Expression of p16 is frequently evaluated in melanocytic lesions. Expression of p16 in cutaneous histiocytic, fibrohistiocytic and undifferentiated lesions has not been well characterized.

METHODS

We evaluated p16 expression in a cohort of histiocytic (reticulohistiocytoma, Langerhans cell histiocytosis, xanthogranuloma, Rosai Dorfman disease and xanthoma), fibrohistiocytic (dermatofibroma, epithelioid fibrous histiocytoma and dermatofibrosarcoma protuberans) and undifferentiated (atypical fibroxanthoma and pleomorphic undifferentiated sarcoma) lesions. A group of melanocytic lesions (Spitz nevus, ordinary nevus, spitzoid melanoma and non-spitzoid melanoma) were also evaluated as reference. Each case was scored by the proportion of p16-positive cells and by staining intensity.

RESULTS

Immunoreactivity for p16 was found in almost all histiocytic (28/30, 93%) and fibrohistiocytic (22/24, 92%) lesions. About half of the undifferentiated lesions also exhibited p16 staining (9/17, 53%). Most of the melanocytic cases examined in this study expressed p16. A wide range of staining intensity and proportion of p16-positive cells was observed in most groups.

CONCLUSION

Expression of p16 is common, albeit variable in proportion and intensity, amongst a wide variety of cutaneous histiocytic, fibrohistiocytic and undifferentiated lesions. Further studies are required to determine if p16 expression is useful in distinguishing benign from malignant neoplasms of these types.

Next generation sequencing of Cytokeratin 20-negative Merkel cell carcinoma reveals ultraviolet-signature mutations and recurrent TP53 and RB1 inactivation

Merkel cell carcinoma is a rare but highly aggressive cutaneous neuroendocrine carcinoma. Cytokeratin 20 (CK20) is expressed in ~95% of Merkel cell carcinomas and is useful for distinction from morphologically similar entities including metastatic small-cell lung carcinoma. Lack of CK20 expression may make diagnosis of Merkel cell carcinoma more challenging, and has unknown biological significance. Approximately 80% of CK20-positive Merkel cell carcinomas are associated with the oncogenic Merkel cell polyomavirus. Merkel cell carcinomas lacking Merkel cell polyomavirus display distinct genetic changes from Merkel cell polyomavirus-positive Merkel cell carcinoma, including RB1 inactivating mutations. Unlike CK20-positive Merkel cell carcinoma, the majority of CK20-negative Merkel cell carcinomas are Merkel cell polyomavirus-negative, suggesting CK20-negative Merkel cell carcinomas predominantly arise through virus-independent pathway(s) and may harbor additional genetic differences from conventional Merkel cell carcinoma. Hence, we analyzed 15 CK20-negative Merkel cell carcinoma tumors (10 Merkel cell polyomavirus-negative, four Merkel cell polyomavirus-positive, and one undetermined) using the Ion Ampliseq Comprehensive Cancer Panel, which assesses copy number alterations and mutations in 409 cancer-relevant genes. Twelve tumors displayed prioritized high-level chromosomal gains or losses (average 1.9 per tumor). Non-synonymous high-confidence somatic mutations were detected in 14 tumors (average 11.9 per tumor). Assessing all somatic coding mutations, an ultraviolet-signature mutational profile was present, and more prevalent in Merkel cell polyomavirus-negative tumors. Recurrent deleterious tumor suppressor mutations affected TP53 (9/15, 60%), RB1 (3/15, 20%), and BAP1 (2/15, 13%). Oncogenic activating mutations included PIK3CA (3/15, 20%), AKT1 (1/15, 7%) and EZH2 (1/15, 7%). In conclusion, CK20-negative Merkel cell carcinoma display overlapping genetic changes with CK20-positive Merkel cell carcinoma, including RB1 mutations restricted to Merkel cell polyomavirus-negative tumors. However, some CK20-negative Merkel cell carcinomas harbor mutations not previously described in Merkel cell carcinoma. Hence, CK20-negative Merkel cell carcinomas harbor diverse oncogenic drivers which may represent therapeutic targets in individual tumors.

Atypical Spitz Tumors: A Diagnostic Challenge

Spitzoid melanocytic lesions encompass a spectrum from benign Spitz nevi to malignant spitzoid melanomas. Spitzoid melanocytic neoplasms have significant morphologic and molecular differences from conventional melanocytic lesions, and prediction of biologic behavior and metastatic risk may be difficult. Most challenging is the atypical Spitz tumor, a borderline spitzoid melanocytic lesion of uncertain malignant potential that has overlapping histologic features with conventional Spitz nevus and spitzoid melanoma. Atypical Spitz tumors involve the sentinel lymph nodes at a greater frequency than conventional melanoma and frequently harbor chromosomal copy number changes, yet most cases follow an indolent course. Herein we review the clinical, microscopic, and molecular features of atypical Spitz tumors, including recent molecular advances, including the potential prognostic significance of chromosomal abnormalities, such as homozygous CDKN2A loss.

Screening for germline mismatch repair mutations following diagnosis of sebaceous neoplasm

IMPORTANCE Sebaceous neoplasms (SNs) define the Muir-Torre syndrome variant of Lynch syndrome (LS), which is associated with increased risk for colon and other cancers necessitating earlier and more frequent screening to reduce morbidity and mortality.Immunohistochemical (IHC) staining for mismatch repair (MMR) proteins in SNs can be used to screen for LS, but data on subsequent germline genetic testing to confirm LS diagnosis are limited.OBJECTIVE To characterize the utility of IHC screening of SNs in identification of germline MMR mutations confirming LS.DESIGN, SETTING, AND PARTICIPANTS Retrospective study at 2 academic cancer centers of 86 adult patients referred for clinical genetics evaluation after diagnosis of SN.MAIN OUTCOMES AND MEASURES Results of tumor IHC testing and germline genetic testing were reviewed to determine positive predictive value and sensitivity of IHC testing in diagnosis of LS. Clinical variables, including age at diagnosis of SN, clinical diagnostic criteria for LS and Muir-Torre syndrome, and family history characteristics were compared between mutation carriers and noncarriers.RESULTS Of 86 patients with SNs, 25 (29%) had germline MMR mutations confirming LS.Among 77 patients with IHC testing on SNs, 38 (49%) had loss of staining of 1 or more MMR proteins and 14 had germline MMR mutations. Immunohistochemical analysis correctly identified 13 of 16 MMR mutation carriers, corresponding to 81% sensitivity. Ten of 12 patients(83%) with more than 1 SN had MMR mutations. Fifty-two percent of MMR mutation carriers did not meet clinical diagnostic criteria for LS, and 11 of 25 (44%) did not meet the clinical definition of Muir-Torre syndrome. CONCLUSIONS AND RELEVANCE Immunohistochemical screening of SNs is effective in identifying patients with germline MMR mutations and can be used as a first-line test when LSis suspected. Abnormal IHC results, including absence of MSH2, are not diagnostic of LS and should be interpreted cautiously in conjunction with family history and germline genetic testing. Use of family history to select patients for IHC screening has substantial limitations,suggesting that universal IHC screening of SNs merits further study. Clinical genetics evaluation is warranted for patients with abnormal IHC test results, normal IHC test results with personal or family history of other LS-associated neoplasms, and/or multiple SNs.

Cutaneous basal cell carcinosarcomas: evidence of clonality and recurrent chromosomal losses

Cutaneous carcinosarcomas are heterogeneous group of tumors composed of malignant epithelial and mesenchymal components. Although mutation analyses have identified clonal changes between these morphologically disparate components in some subtypes of cutaneous carcinosarcoma, few cases have been analyzed thus far. To our knowledge, copy number variations (CNVs) and copy-neutral loss of heterozygosity (CN-LOH) have not been investigated in cutaneous carcinosarcomas. We analyzed 4 carcinosarcomas with basal cell carcinoma and osteosarcomatous components for CNVs/CN-LOH by comparative genomic hybridization/single-nucleotide polymorphism array, TP53 hot spot mutations by polymerase chain reaction and Sanger sequencing, and TP53 genomic rearrangements by fluorescence in situ hybridization. All tumors displayed multiple CNV/CN-LOH events (median, 7.5 per tumor). Three of 4 tumors displayed similar CNV/CN-LOH patterns between the epithelial and mesenchymal components within each tumor, supporting a common clonal origin. Recurrent changes included allelic loss at 9p21 (CDKN2A), 9q (PTCH1), and 17p (TP53). Allelic losses of chromosome 16 including CDH1 (E-cadherin) were present in 2 tumors and were restricted to the sarcomatous component. TP53 mutation analysis revealed an R248L mutation in both epithelial and mesenchymal components of 1 tumor. No TP53 rearrangements were identified. Our findings indicate that basal cell carcinosarcomas harbor CNV/CN-LOH changes similar to conventional basal cell carcinoma, with additional changes including recurrent 9p21 losses and a relatively high burden of copy number changes. In addition, most cutaneous carcinosarcomas show evidence of clonality between epithelial and mesenchymal components.

Vascular neoplasm or pseudovascular nevus? Potential pitfalls in diagnosis

Melanocytic nevi, on histopathologic evaluation, occasionally contain slit-like clefts or spaces that may resemble vascular or lymphatic spaces. The spaces may contain blood or, perhaps more concerning, nests of melanocytes that could suggest lymphatic invasion of melanoma. When lined by melanocytes rather than true endothelium, these pseudovascular spaces within melanocytic nevi are generally attributable to tissue processing artifact. When the space in question is pronounced, a proper diagnostic work-up is prudent in order to exclude a true vascular neoplasm or melanoma. In this case series we present several melanocytic lesions with prominent vascular-appearing spaces that warranted further investigation.