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Derm News: 2007.26(3)

Melanoma associated with a dermatofibroma

Journal of Cutaneous Pathology, 34(5):420-422
Bradley T. Kovach, Alan S. Boyd


Dermatofibromas are common benign cutaneous fibrohistiocytic neoplasms, whereas melanomas are potentially aggressive malignancies. Differentiating these two entities can occasionally be difficult.


We report the case of a 56-year-old female presenting with a firm pink papule on the left thigh.


Histopathology revealed atypical melanocytes in the epidermis and papillary dermis with numerous mitotic figures and intraepidermal pagetoid spread. Within the dermis was a poorly demarcated collection of epithelioid and spindled cells with intermixed keloidal collagen. The atypical melanocytes stained for MART-1 and S-100, whereas the underlying fibrohistiocytic tumor took up factor XIIIa immunostain, confirming the diagnosis of invasive malignant melanoma occurring in association with a dermatofibroma.


This case emphasizes the role of immunohistochemical stains in correctly diagnosing melanocytic and histiocytic neoplasms.

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The Derm News service provided by the Editorial Consultants of Skin Therapy Letter© and its founding editor Dr. Stuart Maddin.