Post‐Radiation Malignant Fibrous Histiocytoma Following Treatment of Eruptive Squamous Cell Carcinoma In‐Situ in an African American Male

Abstract

A 32‐year‐old African American male presented with a five year history of multiple verrucous plaques in a Blaschkoid arrangement on the left leg. Biopsies demonstrated squamous cell carcinoma in‐situ. The patient’s medical history did not reveal any heritable or exposure related risk factors. The patient was treated with radiotherapy. Four years later, he presented with a subcutaneous nodule within a prior site of radiation. MRI showed a 2.0 × 1.2 cm enhancing nodule in the subcutis. On biopsy, an ill‐defined spindle cell proliferation was present in the dermis and subcutis. Marked nuclear pleomorphism and numerous multinucleated cells embedded in a myxoid stroma were noted. Spindle cells stained for CD68. Cytokeratin and S‐100 were negative. A diagnosis of Malignant Fibrous Histiocytoma was rendered. Surgical excision was undertaken. A dominant lesion of MFH was identified, as well as multiple, clinically undetectable foci of early sarcoma. This is an unusual case of multifocal post‐radiation sarcoma in an African American patient with squamous cell carcinoma in‐situ. While sarcoma is a known risk factor following radiotherapy, the course of this patient would suggest caution in applying radiation in similar clinical settings, as well as long‐term clinical follow‐up for early detection and treatment of post‐radiation sarcoma.