Track

Case Reports

Abstract

Epidermolytic acanthoma (EA) is a rare, acquired, benign keratosis that typically presents as single lesions in middle-aged to elderly patients, characterized by histopathologic findings similar to epidermolytic ichthyosis. Recently, KRT10 hotspot mutations have been shown in a subset of EAs. While often postulated to result from trauma, EA developing in a post-radiation setting has never been reported in the literature. Herein, we report the case of a 59-year-old woman, 5 months following definitive chemoradiation therapy for HPV-dependent anal squamous cell carcinoma, presenting with a new perianal skin nodule, concerning for local recurrent cancer. Biopsy revealed a benign keratosis with diffuse cytoplasmic vacuolar degeneration, eosinophilic globoid bodies, and hyperorthokeratosis, characteristic of EA. Additionally, there were dermal stellate fibroblasts consistent with post-radiation changes. Differentiating epidermolytic changes and HPV-related cytopathic effect was particularly important given the history of HPV-dependent squamous cell carcinoma. To our best knowledge, this is the first EA associated with radiation therapy reported in the literature. Interestingly, a plausible link may exist between radiation and pathogenic somatic mutations leading to EA. Our case contributes to the growing knowledge of EA and post-radiation skin changes and expands the differential diagnosis in this clinical scenario.