Abstract
Cutaneous desmoplastic melanoma (DM) is an uncommon variant of spindle cell melanoma accounting for less than 4% of primary melanomas of the skin. The most common clinical presentation is a firm nonpigmented nodule or plaque on severely sun-damaged skin of elderly male individuals.1 Histologically, DM is a heterogeneous group of melanocytic tumors phenotypically ranging from a scar-like paucicellular proliferation of bland fusiform melanocytes separated by a dense collagenous stroma to high-grade sarcoma-like pleomorphic spindled cells with a variable degree of stromal desmoplasia.2-7 An atypical junctional melanocytic proliferation in the overlying epidermis and lymphocytic aggregates at the periphery of the tumor are often a feature, representing useful diagnostic clues, although the so-called DM arising "de novo" lacks a junctional melanocytic component.8 Histopathological variations in DM include striking neurotropism with perineural and endoneurial invasion (neurotropic desmoplastic melanoma),9 prominent Schwannian and perineural features (neural transformation),10 marked myoid/myofibroblastic differentiation in the stroma, and others.11,12 Molecular analysis of DM reveals a high-mutation burden, ultraviolet (UV) signature, and frequent mutations in NF1 (55%), TP53 (48%), and CDKN2A (47%).13-16 In this article, we present a very unusual case of neurotropic DM with collagen rosette formation, clear cell change, epithelioid cells, and pseudoglandular features.