Subungual malignant melanoma with cartilaginous differentiation

A case of subungual malignant melanoma with cartilaginous differentiation i s presented and the phenomenon of sarcomatoid differentiation in malignant melanoma reviewed. Osseous and/or cartilaginous (osteocartilaginous) differ entiation of malignant melanoma is rare. Only 14 cases have previously been reported. This small number of cases and the subject of this Case Report h ave several features in common, including acral (particularly subungual) lo cation, high Breslow thickness, presence of a lentiginous radial growth pha se component, and predominance of epithelioid melanocytes with amelanotic c ytoplasm. Melanoma with osteocartilaginous differentiation may therefore re present a subgroup of melanoma with distinctive clinical and pathologic fea tures. Further study is required to establish whether any unique molecular or genetic features are also present.