Foamy Cell Angiosarcoma in a Patient with Xeroderma Pigmentosum: A Case Report and Comprehensive Review of the Literature.

Xeroderma pigmentosum (XP) is a rare autosomal recessive disorder characterized by a DNA repair defect caused by ultraviolet light and cutaneous manifestations, including solar lentigines, xerosis, actinic damage, and cutaneous neoplasms (e.g., basal cell carcinoma, squamous cell carcinoma, and melanoma). Cutaneous angiosarcoma (AS) is a rare group of aggressive skin tumors that infrequently occur in patients with XP, usually involving the scalp or face. The AS has three subtypes: idiopathic, complicating lymphedema, and post-irradiation. The AS has diverse histopathological types, and the uncommon variants are clear cell, epithelioid, granular cell, pseudo lymphomatous, verrucous, and signet-ring cell variants. Although the foamy cell variant of AS is the rarest type, its diagnosis would be really challenging due to the wide variety of differential diagnoses, especially for poorly differentiated ones. Therefore, definitive diagnosis and effective management in the early stages are crucial, and immunohistochemical (IHC) tests are essential. Here we report a 50-year-old Iranian man with AS complicating XP who presented with an ulcerative erythematous and progressive plaque. Histopathologic studies revealed foamy cells and vascular markers (i.e., CD 31 and CD 34) were positive, immunohistochemically which was found unusual features. In addition,, we review previously reported cases in the literature to provide some information on the diagnosis and management of such cases.