Subungual Malignant Melanoma With Cartilaginous DifferentiationCachia, Adrian R. F.R.C.P.A.; Kedziora, Andrew M. M.B., B.S.The American Journal of Dermatopathology: April 1999 - Volume 21 - Issue 2 - p 165-169 Extraordinary Case Reports Abstract Author Information A case of subungual malignant melanoma with cartilaginous differentiation is presented and the phenomenon of sarcomatoid differentiation in malignant melanoma reviewed. Osseous and/or cartilaginous (osteocartilaginous) differentiation of malignant melanoma is rare. Only 14 cases have previously been reported. This small number of cases and the subject of this Case Report have several features in common, including acral (particularly subungual) location, high Breslow thickness, presence of a lentiginous radial growth phase component, and predominance of epithelioid melanocytes with amelanotic cytoplasm. Melanoma with osteocartilaginous differentiation may therefore represent a subgroup of melanoma with distinctive clinical and pathologic features. Further study is required to establish whether any unique molecular or genetic features are also present. From the Department of Tissue Pathology, Institute of Clinical Pathology and Medical Research, Westmead Hospital, Westmead, Australia. Address correspondence to Adrian R. Cachia, Department of Tissue Pathology, Institute of Clinical Pathology and Medical Research, Westmead Hospital, Westmead, NSW 2145, Australia. © 1999 Lippincott Williams & Wilkins, Inc.