A unique biphasic variant of cutaneous fibrous histiocytoma with a storiform pattern and intralesional pigmented melanocytes: “storiform melano-fibrous histiocytoma”

Abstract

Dermatofibromas (cutaneous fibrous histiocytomas) are common cutaneous neoplasms of mesenchymal origin. They are often associated with epidermal hyperplasia and increased basal layer pigmentation. There have been reports of a spectrum of melanocytic lesions associated with dermatofibromas ranging from junctional nevi to malignant melanomas, some of which may be coincidentally associated. We report a case of a long-standing storiform fibrohistiocytic lesion devoid of cytological atypia, lacking extension into subcutaneous fat, not demonstrating the t(17;22) DFSP translocation yet showing diffuse and strong CD34 immunoreactivity and containing pigmented spindle shaped melanocytic cells admixed with the fibrohistiocytic component. This case raises a nosological debate given the histological, immunophenotypic and cytogenetic findings.

Part of CIRS Nexus · Curated by Lauren Lowenstein, The Biotoxin Lady