Diagnostic Challenge of Desmoplastic Melanoma.

Desmoplastic melanoma (DM) is a rare variant of spindle-cell malignant melanoma. DM is easily misdiagnosed at an early stage because it can be confused with benign entities. Histological analysis, including careful attention to the presence of atypical spindle cells, as well as to lymphocytic aggregates in an abundant fibrotic stroma in the dermis, provides clues for diagnosis. The adjunction of an immunohistochemical panel, and particularly testing for S-100 protein, is needed for the final diagnosis.