Angiosarcoma of the Scalp Mimicking an Inflammatory Scarring Alopecia and Diagnosed on Horizontal Histologic Sections.

While most forms of alopecia neoplastica are attributable to cutaneous metastases from visceral primary malignancies, rarely a diffuse primary skin cancer may present as alopecia. Herein, we present a case of angiosarcoma which clinically mimicked an inflammatory alopecia and was diagnosed by examination of alopecia-protocol horizontal histologic sections. A 72-year-old female presented to her dermatologist with a chief complaint of hair loss and pruritus. She was noted to have alopecia with erythema of the scalp and was diagnosed clinically with lichen planopilaris. However, when multiple topical treatments were unsuccessful, her dermatologist performed a scalp biopsy to guide further alopecia therapy. Horizontally oriented histologic sections were prepared from the biopsy in standard alopecia fashion. Histopathologic examination revealed a proliferation of dissecting vascular channels lined by atypical endothelial cells, diagnostic of angiosarcoma. The patient underwent radiation and chemotherapy with clinical response and had stable disease for several years thereafter. This case highlights the importance of considering unexpected malignancies in the clinical and pathologic examination of cases of suspected inflammatory alopecia.