Genomic and Transcriptomic Underpinnings of Melanoma Genesis, Progression, and Metastasis.

Melanoma is a deadly skin cancer with rapidly increasing incidence worldwide. The discovery of the genetic drivers of melanomagenesis in the last decade has led the World Health Organization to reclassify melanoma subtypes by their molecular pathways rather than traditional clinical and histopathologic features. Despite this significant advance, the genomic and transcriptomic drivers of metastatic progression are less well characterized. This review describes the known molecular pathways of cutaneous and uveal melanoma progression, highlights recently identified pathways and mediators of metastasis, and touches on the influence of the tumor microenvironment on metastatic progression and treatment resistance. While targeted therapies and immune checkpoint blockade have significantly aided in the treatment of advanced disease, acquired drug resistance remains an unfortunately common problem, and there is still a great need to identify potential prognostic markers and novel therapeutic targets to aid in such cases.

Panniculitis in a patient with pathologic complete response to talimogene laherparepvec treatment for recurrent, in-transit melanoma.

Talimogene laherparepvec (T-VEC) is a novel intralesional oncolytic genetically modified herpes simplex virus type 1 vector for the treatment of unresectable cutaneous, subcutaneous, and nodal melanoma. Although immunological therapies such as T-VEC offer therapeutic promise, they carry a risk of immune-related adverse events (irAEs), the full spectrum of which is incompletely understood. We report a 63-year-old previously healthy man with cutaneous melanoma of the right ankle and progressive right lower extremity in-transit metastases despite systemic therapy with immunomodulatory and molecularly targeted treatments. T-VEC treatment resulted in a complete pathologic response on scouting biopsies. Biopsy of the right lateral calf showed lobular and septal panniculitis with lymphoplasmacytic infiltrate and lipophages. Gomori methenamine silver (GMS) stain and acid-fast bacilli (AFB) stains were negative, and no polarizable foreign material was noted. T-VEC was discontinued due to complete pathologic response and, in part, concern for development of irAEs including this panniculitis and an early concomitant autoimmune colitis. This case highlights a previously unreported irAE with this novel treatment for advanced cases of melanoma.

Cutaneous angiosarcoma clinically presenting as progressive solid facial edema in a 43-year-old male.

Cutaneous angiosarcoma of the head and neck is a rare, highly malignant neoplasm; prognosis is heavily influenced by tumor size, resectability, and stage at initial diagnosis. Most patients present with one to several erythematous to violaceous patches, plaques, or nodules. However, the clinical presentation is highly variable and leads to delayed diagnosis. We report cutaneous angiosarcoma in a 43-year-old man who presented with an 11-month history of progressive solid (non-pitting) edema involving his entire face, scalp, eyelids, and neck without characteristic clinical features of cutaneous angiosarcoma. A skin biopsy had shown non-specific findings consistent with solid facial edema or rosacea. Various etiologies were considered but there was no significant improvement after directed medical therapy. Repeat skin biopsies revealed angiosarcoma involving the dermis and sub-cutis. Computed tomography (CT) of the chest showed multiple lung nodules bilaterally and a lytic lesion in the T6 vertebra consistent with metastases. He was treated with single agent chemotherapy (paclitaxel), and had a partial response that restored his ability to open both eyes spontaneously; However, his edema has recently progressed 7 months after diagnosis. This is a rare example of cutaneous angiosarcoma presenting as progressive solid facial edema, which underscores the diverse range of clinical manifestations associated with this neoplasm.

p63 expression in Merkel cell carcinoma predicts poorer survival yet may have limited clinical utility.

OBJECTIVES: To determine the clinical utility of p63 expression, which has been identified in several cohorts as a predictor of poorer prognosis in Merkel cell carcinoma (MCC). METHODS: Immunohistochemistry was used to determine p63 expression on MCC tumors from 128 patients. RESULTS: Of the patients, 33% had detectable p63 expression. p63 Positivity was associated with an increased risk of death from MCC (hazard ratio, 2.05; P = .02) in a multivariate Cox regression model considering stage at presentation, age at diagnosis, and sex. Although p63 expression correlated with diminished survival in this largest cohort reported thus far, the effect was weaker than that observed in prior studies. Indeed, within a given stage, p63 status did not predict survival in a clinically or statistically significant manner. CONCLUSIONS: It remains unclear whether this test should be integrated into routine MCC patient management.

Langerhans cell sarcoma in a patient with hairy cell leukemia: common clonal origin indicated by identical immunoglobulin gene rearrangements.

Histiocytic/dendritic cell sarcomas are rare tumors, a few of which have been reported in association with B-cell lymphoma/leukemia. Isolated reports have documented identical immunoglobulin gene rearrangements suggesting a common clonal origin for both the sarcoma and the B-cell neoplasm from individual patients. We report a case of a 75-year-old male with hairy cell leukemia who subsequently developed Langerhans cell sarcoma 1 year after his primary diagnosis of leukemia. The bone marrow biopsy containing hairy cell leukemia and skin biopsies of Langerhans cell sarcoma were evaluated by routine histology, immunohistochemistry, flow cytometric immunophenotyping and PCR-based gene rearrangement studies of the immunoglobulin heavy chain and kappa genes. The hairy cell leukemia showed characteristic morphologic, immunohistochemical and flow cytometric features. The Langerhans cell sarcoma showed pleomorphic cytology, a high mitotic rate and characteristic immunohistochemical staining for Langerin, S100 and CD1a. There was no evidence of B-cell differentiation or a background B-cell infiltrate based on the absence of immunoreactivity with antibodies to multiple B-cell markers. Identical immunoglobulin gene rearrangements were identified in both the hairy cell leukemia and Langerhans cell sarcoma specimens. Despite the phenotypic dissimilarity of the two neoplasms, identical immunoglobulin gene rearrangements indicate a common origin.

Analysis of Tp53 codon 72 polymorphisms, Tp53 mutations, and HPV infection in cutaneous squamous cell carcinomas.

BACKGROUND: Non-melanoma skin cancers are one of the most common human malignancies accounting for 2-3% of tumors in the US and represent a significant health burden. Epidemiology studies have implicated Tp53 mutations triggered by UV exposure, and human papilloma virus (HPV) infection to be significant causes of non-melanoma skin cancer. However, the relationship between Tp53 and cutaneous HPV infection is not well understood in skin cancers. In this study we assessed the association of HPV infection and Tp53 polymorphisms and mutations in lesional specimens with squamous cell carcinomas. METHODS: We studied 55 cases of histologically confirmed cutaneous squamous cell carcinoma and 41 controls for the presence of HPV infection and Tp53 genotype (mutations and polymorphism). RESULTS: We found an increased number of Tp53 mutations in the squamous cell carcinoma samples compared with perilesional or control samples. There was increased frequency of homozygous Tp53-72R polymorphism in cases with squamous cell carcinomas, while the Tp53-72P allele (Tp53-72R/P and Tp53-72P/P) was more frequent in normal control samples. Carcinoma samples positive for HPV showed a decreased frequency of Tp53 mutations compared to those without HPV infection. In addition, carcinoma samples with a Tp53-72P allele showed an increased incidence of Tp53 mutations in comparison carcinomas samples homozygous for Tp53-72R. CONCLUSIONS: These studies suggest there are two separate pathways (HPV infection and Tp53 mutation) leading to cutaneous squamous cell carcinomas stratified by the Tp53 codon-72 polymorphism. The presence of a Tp53-72P allele is protective against cutaneous squamous cell carcinoma, and carcinoma specimens with Tp53-72P are more likely to have Tp53 mutations. In contrast Tp53-72R is a significant risk factor for cutaneous squamous cell carcinoma and is frequently associated with HPV infection instead of Tp53 mutations. Heterozygosity for Tp53-72R/P is protective against squamous cell carcinomas, possibly reflecting a requirement for both HPV infection and Tp53 mutations.

Keratinocyte dysplasia in hematopoietic stem cell transplantation recipients in the day-28-to-84 posttransplantation period.

Severe keratinocyte dysplasia (SKD) has been reported as a common event in the early posttransplantation period of hematopoietic stem cell transplantation patients. The purpose of our study is to determine the possible causes of SKD during the intermediate posttransplantation period and to ascertain its prevalence in skin biopsies. Skin biopsy slides, obtained from hematopoietic stem cell transplantation recipients who were days 28 to 84 posttransplantation, were evaluated for SKD. Forty-four examples of SKD were identified in 467 slides, or 9%. Thirty-seven patients were evaluated as cases in a case-control design. SKD was strongly associated with a conditioning regimen containing busulfan with an odds ratio of 7.25 (P = .0002). In a multivariate-adjusted analysis, SKD was not associated with cyclophosphamide, fludarabine, total-body irradiation, or a nonmyeloablative conditioning regimen. SKD was not associated with clinical acute graft-versus-host disease. SKD histology gradually resolved, reaching a normal histology after an average of 241 days. This study finds that severe keratinocyte dysplasia in the period 28 to 84 days post-HSCT is strongly associated with a busulfan-conditioning regimen.

Agminated cellular neurothekeoma.

Cellular neurothekeoma represents a benign, slow-growing neoplasm that typically occurs as a solitary lesion on the face, neck or arm. Reports of multiple lesions are rare. To our knowledge, multiple lesions occurring as eruptive clusters localized to a single anatomical site has not been previously reported. This report details a case of an agminated cellular neurothekeoma occurring on the nose of a 28-year-old man. Recognition of multiple localized eruptive lesions of cellular neurothekeoma is important in order to facilitate correct diagnosis and avoid unnecessary treatment.

Flow cytometric evaluation of skin biopsies for mycosis fungoides.

Multicolor flow cytometry (FC) is indispensable for lymphoma diagnosis and classification, but its utility in evaluating skin biopsies for mycosis fungoides (MF) is not well established. We describe the largest series to date of skin biopsies evaluated by FC for MF (n = 33), and we compare the flow cytometric results with the histologic, molecular, and clinical findings. Abnormal T-cell populations were identified by FC in 14 of 18 patients (78%) having histologically confirmed MF and in no patient whose histology was negative or indeterminate for MF (n = 14). One patient had histologic, flow cytometric, and molecular findings compatible with MF, but this patient's clinical course was more suggestive of a drug eruption. Fourteen of 15 abnormal T-cell populations showed definitive aberrant expression of at least 2 surface antigens, including CD2 (47%), CD3 (67%), CD4, CD5 (87%), CD7, and CD45 (67%); most cases (67%) had light scatter properties suggesting increased cell size and/or cytoplasmic complexity. The high specificity of FC suggests that it will be a useful adjunct to routine histology in the evaluation of diagnostic skin biopsies for MF.

Ancient melanocytic nevus: a simulator of malignant melanoma.

Ancient melanocytic nevus (AN) is an unusual but distinctive melanocytic neoplasm within the spectrum of simulators of malignant melanoma. This report describes 13 patients with AN where a long follow-up information was available. Histopathology is characterized by 2 populations of melanocytes, namely, one with large pleomorphic cells and the other with small melanocytes. A few mitotic figures may be present exceptionally. MIB-1 (Ki67) proliferation marker reveals an overall low nuclear labeling index. Additional important findings are stromal degenerative changes. AN must be especially differentiated from dermal melanoma arising in a nevus.

Transcriptome-wide studies of merkel cell carcinoma and validation of intratumoral CD8+ lymphocyte invasion as an independent predictor of survival.

PURPOSE: Merkel cell carcinoma (MCC) is a polyomavirus-associated skin cancer that is frequently lethal and lacks established prognostic biomarkers. This study sought to identify biomarkers that improve prognostic accuracy and provide insight into MCC biology. PATIENTS AND METHODS: Gene expression profiles of 35 MCC tumors were clustered based on prognosis. The cluster of genes overexpressed in good-prognosis tumors was tested for biologic process enrichment. Relevant mRNA expression differences were confirmed by quantitative polymerase chain reaction and immunohistochemistry. An independent set of 146 nonoverlapping MCC tumors (median follow-up, 25 months among 116 living patients) was employed for biomarker validation. Univariate and multivariate Cox regression analyses were performed. RESULTS: Immune response gene signatures were prominent in patients with good prognoses. In particular, genes associated with cytotoxic CD8+ lymphocytes were overexpressed in tumors from patients with favorable prognoses. In the independent validation set, cases with robust intratumoral CD8+ lymphocyte infiltration had improved outcomes (100% MCC-specific survival, n = 26) compared with instances characterized by sparse infiltration (60% survival, n = 120). Only stage and intratumoral CD8 infiltration (but not age, sex, or CD8+ lymphocytes localized to the tumor-stroma interface) were significant in both univariate and multivariate Cox regression analyses. Notably, traditional histologic identification of tumor-infiltrating lymphocytes was not a significant independent predictor of survival. CONCLUSION: Intratumoral CD8+ lymphocyte infiltration can be readily assessed on paraffin-embedded tissue, is independently associated with improved MCC-specific survival, and therefore, may provide prognostic information that enhances established MCC staging protocols.

Diagnosis of mycosis fungoides with different algorithmic approaches.

BACKGROUND: Algorithmic scoring approaches for evaluating early cases of mycosis fungoides (MF) provide a degree of diagnostic standardization. At the UWMC, biopsies from clinically concerning cases for MF are individually reviewed by a panel of pathologists and an average score is assigned to each biopsy reflecting the degree of suspicion for a diagnosis of MF; however, such an approach may not be practical outside of an academic center. METHODS: 78 cases characterized in our institution, with the diagnosis confirmed by clinicopathologic correlation/clinical follow-up were evaluated with two different algorithms, based entirely on histologic evaluation (Guitart algorithm) and partial implementation of the ISCL algorithm evaluating histology, immunohistochemistry and T-cell clonality. RESULTS: A receiver operating characteristic curve comparing the results of the two approaches in early MF cases showed no statistical difference between the areas under the two curves. Increased stages of MF showed variable loss of T-cell antigens by immunohistochemistry and higher rates of detectable clonality. CONCLUSION: We could not document a statistically significant advantage of adding ancillary immunohistochemical and molecular testing to careful histologic evaluation in the workup of suspected cases of early MF. A systemic approach to histologic diagnosis by a single pathologist correlated favorably to the MF panel diagnosis.

Expanding the clinicopathologic spectrum of palisaded encapsulated neuroma.

Palisaded encapsulated neuroma (PEN; solitary circumscribed neuroma) is a benign, morphologically characteristic cutaneous or mucosal neuroma. Most are solitary lesions on the face, neck or oral mucosa. Histologically, the majority appears as dermal nodules of Schwann cell-rich fascicles, with or without distinctive encapsulation. To further expand on the existing literature regarding this neuroma, we herein describe three PENs with unique clinical and histopathologic features. All occurred on the acral skin, a rarely described site. Furthermore, one exceptional patient presented with multiple PEN on the bilateral hands, biopsies of which showed a prominent plexiform architecture. Awareness that PEN may occur on acral skin, may rarely present as multiple lesions, and recognition of the plexiform variant is important because PEN may histologically mimic other peripheral nerve sheath tumors. Additionally, misdiagnosis may have significant clinical implications.

Atypical neurofibroma of the skin and subcutaneous tissue: clinicopathologic analysis of 11 cases.

BACKGROUND: Neurofibroma (NF) is a relatively common cutaneous tumor, which typically presents little diagnostic difficulty. Occasionally, however, pleomorphic cells may be present in NF raising consideration of other neoplasms like malignant peripheral nerve sheath tumor (MPNST). METHODS: This study examines the clinicopathologic and immunohistochemical features of 11 dermal and subcutaneous 'atypical' NF. RESULTS: 9/11 (82%) atypical NF were from females, aged 8-70 years. One patient had neurofibromatosis-1. Most presented on the extremities or trunk. The atypical cells had large hyperchromatic, irregular nuclei, and were arranged in a distinct lamellar or fibrillar pattern. Some tumors were hypercellular, but marked density characteristic of MPNST was not observed. All were nonplexiform. Mitoses were mostly absent. The pleomorphic cells expressed S-100 protein. All were negative for p53. MIB-1 was negative in 7/10 (70%) and stained only rare cells in 3 (30%). Epithelial membrane antigen (EMA) and p16 expression were variable. Of six patients with available follow-up, no tumor recurred and none developed malignancy (range 6-63, mean 33 months). CONCLUSIONS: Superficial atypical NF, while morphologically unusual, has no apparent association with neurofibromatosis-1 or short-term risk of recurrence or malignant transformation. Awareness of this variant is important in order to avoid misdiagnosis of a more aggressive neoplasm.

S100, HMB-45, and Melan-A negative primary melanoma.

The diagnosis of malignant melanoma can be challenging given the wide variation in morphologic features and immunohistochemical stains are often used to confirm the diagnosis. We report a case of melanoma with loss of staining for S100 protein, HMB-45, and Melan-A, with retained expression of tyrosinase. Regional lymph node metastases showed positive S100 protein staining. Although the loss of phenotypic markers including S100 protein has been reported in metastatic melanoma, loss of S100 in primary melanoma is rare. Discordant staining between primary and metastatic lesions further emphasizes the protean nature of melanoma.

Histiocyte-rich pleomorphic mastocytoma: an uncommon variant mimicking juvenile xanthogranuloma and Langerhans cell histiocytosis.

An 11-year old Caucasian female with a remote history of urticaria pigmentosa presented with a neck mass. A biopsy demonstrated a large intradermal nodule composed of unusually large epithelioid mast cells, including a prominent subset with bi-lobed and multi-lobed nuclei. By immunohistochemistry, the cells expressed CD117 (C-Kit), mast cell tryptase, CD68, and CD25, and were negative for CD163, CD1a, and S-100, confirming the diagnosis of mastocytoma. Equally prominent was an admixed infiltrate of CD68 and CD163-positive xanthomatous histiocytes that included Touton-type giant cells. Eosinophils were abundant. At 7 months follow-up, there was no recurrence of the lesion following complete excision. However, given the unusual cytologic features, close clinical observation is warranted, as the long-term biologic potential of mastocytoma with this degree of cytologic atypia is uncertain. Awareness of this unusual morphologic variant is also important as the histologic features may mimic such childhood neoplasms as juvenile xanthogranuloma and Langerhans cell histiocytosis.

An infiltrative variant of non-neural granular cell tumor: a case report.

Dermal non-neural granular cell tumors are rare tumors of indeterminate lineage that typically present as well-circumscribed tumors with nuclear pleomorphism and mitotic activity. We describe a dermal non-neural granular cell tumor with a distinctive growth pattern with granular cells interspersed between collagen bundles. This asymptomatic papule arose on the scapula of a 46-year-old woman and consisted of a mixture of epithelioid and spindled granular cells. The immunohistochemical characteristics were similar to those of previously reported dermal non-neural granular cell tumors. Despite mild nuclear pleomorphism and dispersion of lesional cells among collagen bundles, mitoses were not present and Ki-67 staining indicated a low proliferative rate. In addition to being S-100 protein negative and NKI/C3 positive, our case was positive for PGP9.5 and weakly positive for neuron-specific enolase, a staining pattern similar to what has been observed for cellular neurothekeomas. Our case could represent a dermal non-neural granular cell tumor with unique architecture, a granular cellular neurothekeoma or a granular cell dermatofibroma. As both dermal non-neural granular cell tumor and cellular neurothekeoma are of indeterminate lineage, our case with features characteristic of both entities may suggest a common precursor or lineage for dermal non-neural granular cell tumor and cellular neurothekeoma.