An otherwise healthy man in his 50s was referred to the Department of Dermatology with a 5-year history of an asymptomatic, gradually enlarging, reddish hematomalike plaque with a brownish peripheral border in his left axilla (Figure 1). The patient described the spontaneous onset of the lesion and reported no previous history of trauma or any other systemic symptoms; he had previously applied a topical antifungal cream but observed no lesion improvement. Physical examination revealed a nonindurated and well-defined 10 × 8-cm reddish-brown annular plaque with peripheral ecchymosis. No local lymphadenopathy was observed. Two biopsy specimens were obtained from different areas of the lesion for immunohistochemical studies; vascular channel endothelial cells were positive for CD31, CD34, and D2-40 and negative for human herpesvirus 8 (HHV-8) (latent nuclear antigen) and Wilms tumor 1 (WT1). Serologic tests for HIV and hepatitis B and C were negative.