Unexpected Angiosarcoma Diagnosis in Scalp Biopsy during Alopecia Evaluation

Summary: Objectives: We present a unique instance of alopecia neoplastica caused by angiosarcoma, where the diagnostic scalp biopsy was processed in horizontal sections for alopecia evaluation. Methods: A 72-year-old woman with a history of Hashimoto’s disease and hypertension presented with several months of hair loss with scalp erythema and pruritus. She had erythematous patches with subtle scale on the parietal and temporal scalp, as well as diffuse thinning of hair. Considering inflammatory alopecia, her dermatologist performed a scalp biopsy to guide alopecia therapy, and this biopsy was processed in horizontal sections. Results: This biopsy revealed a proliferation of dissecting vascular channels lined by atypical endothelial cells positive for cluster of differentiation 31 (CD31), diagnostic of angiosarcoma. The patient underwent radiation and chemotherapy with clinical response and was followed for several years with stable disease. Conclusion: Angiosarcoma can have variable clinical presentations, sometimes resembling other neoplasms. In rare instances, it can mimic inflammatory conditions of the scalp like alopecia. The histopathologic spectrum of cutaneous angiosarcoma includes well-differentiated, epithelioid, and poorly differentiated variants, with diagnosis reliant on immunohistochemistry to confirm vascular differentiation and distinguish from other malignancies. Given the aggressive clinical of angiosarcoma, early recognition and treatment are crucial, especially since other scalp lesions can present similarly.