Pigmented epithelioid melanocytoma: a recently described melanocytic tumour of low malignant potential

Pigmented Epithelioid Melanocytoma: Morphology and Molecular Drivers

Pigmented epithelioid melanocytoma (PEM) was originally described based on keen morphologic analysis identifying a group of melanocytic tumors sharing heavily pigmented epithelioid melanocytes. It is defined as heavily pigmented epithelioid, spindled, and dendritic melanocytes with characteristic vesicular nuclei, prominent nucleoli, and melanophages. PEM often involves regional lymph nodes. Recent advances in molecular analysis have allowed for subclassification of PEM into more specific subsets of melanocytic tumors. The most common subsets include PRKCA fusions, which result in pure PEMs with sheets of monomorphic epithelioid melanocytes, and PEMs with combined pattern and mutations in both PRKAR1A and BRAF.

A Review of Key Biological and Molecular Events Underpinning Transformation of Melanocytes to Primary and Metastatic Melanoma

Melanoma is a major public health concern that is responsible for significant morbidity and mortality, particularly in countries such as New Zealand and Australia where it is the commonest cause of cancer death in young adults. Until recently, there were no effective drug therapies for patients with advanced melanoma however significant advances in our understanding of the biological and molecular basis of melanoma in recent decades have led to the development of revolutionary treatments, including targeted molecular therapy and immunotherapy. This review summarizes our current understanding of the key events in the pathway of melanomagenesis and discusses the role of genomic analysis as a potential tool for improved diagnostic evaluation, prognostication and treatment strategies. Ultimately, it is hoped that a continued deeper understanding of the mechanisms of melanomagenesis will lead to the development of even more effective treatments that continue to provide better outcomes for patients with melanoma.

Animal-type melanoma: dog or wolf? A review of the literature and a case report

The human animal type melanoma (ATM) is a rare subtype of melanoma characterised by the proliferation of pigmented dermal epithelioid and spindled melanocytes. However, this variant of melanoma is still lacking a precise nosography definition and classification for the difficulty to be distinguished from other more common melanocytic lesions, as well as for its peculiar biological behaviour. On the other hand, the contribution of scientific literature to this issue is fragmented and limited to the description of very few cases. Starting from the presentation of a case with abnormally aggressive clinical features, here we revisit the current knowledge on ATM from its dermatologic patterns, epidemiology, demography and histopathology to the clinical management. Peculiar accuracy has also been reserved to several histopathologic criteria, which are critical for the differential diagnosis from other melanocytic diseases in junction with molecular data deriving from recent cytogenetic and mutational characterisation of this tumour.

Animal-type melanoma: report of five cases with sentinel node biopsy and fluorescence in-situ hybridization analysis

Animal-type melanoma (ATM) is a rare tumor, characterized histologically by a predominantly dermal proliferation of heavily pigmented epithelioid and spindle dendritic melanocytes. Five patients with ATM, who had undergone sentinel node biopsy, were studied: three male and two female, between 4 and 62 years of age (mean, 28.0). Lesion size ranged from 4 to 18 mm and thickness from 0.7 to 5.1 mm. Nodal deposits were found in three patients. Of the patients with positive sentinel nodes, the first showed a minimal nodal involvement in one node, the second multiple deposits in one node, and the third multiple deposits in one sentinel node and a single deposit in another; this last patient also had additional tumor deposits in a nonsentinel regional node. Fluorescence in-situ hybridization tumor analysis proved negative in all cases. All patients are alive and free of disease at 36-95-month follow-up (mean, 53 months). Results showed ATM as a neoplasm characterized by a somewhat high rate of lymph node involvement but relatively low rate of visceral metastases and mortality, appearing as a low-grade malignant tumor.

Clinicopathologic features of an infant with generalized congenital epithelioid blue nevi

Since epithelioid blue nevus (EBN) was 1st described in patients with Carney complex, 49 sporadic EBN cases, including 4 congenital EBN, have been reported. We present a 2-month-old healthy female with more than 1000 congenital EBN on the entire body. Skin biopsy revealed many nevus nests located in the upper dermis and a few nests extended around the sweat ducts and hair follicles in the middle and lower dermis. The heavily pigmented melanocytes were substantially epithelioid and occasionally spindle cells, admixed with melanophages. Immunohistochemistry revealed strong staining for S-100 and HMB-45 but weak or moderate staining for Melan-A in dermal melanocytes after melanin bleaching with potassium permanganate and oxalic acid prior to incubation with the primary antibody. A diagnosis of congenital EBN was made based on clinicopathologic and immunopathologic findings.

Animal-type melanoma - tumor cell invasion of dermal lymphatics and molecular identification of lymph node metastasis

Animal-type melanoma (ATM) represents a rare subtype within the wide spectrum of melanocytic tumors. Clinically, ATM lesions appear as sharply demarcated, brown, black and dark blue pigmented nodules, which show grey-white surface elements on dermatoscopy. The tumor is restricted to the dermis and arranged in irregular fascicles, which are composed of spindle-shaped and epithelioid melanocytes. Moderate tumor cell pleomorphism, mitoses and apoptotic cells all suggest a malignant process. Abundant, finely dispersed melanin pigment within tumor cells as well as numerous melanophages are strongly suggestive of ATM. Even though locoregional lymph node metastases are frequently found at diagnosis, the course of ATM is generally benign. Specific molecular changes may be detected in melanocytes from lesions and lymph nodes on fluorescence in situ hybridization (FISH). Such findings strongly indicate the malignant potential of ATM. The peculiar biology of ATM, as a moderately malignant tumor, is reflected in a new histopathological classification within the spectrum of dermal borderline melanocytic tumors (BMT).