Thrombosed angiokeratoma is a cutaneous vascular lesion that may resemble melanoma. This paper discusses the cases of thrombosed angiokeratoma seen in a five-year period at the Dermatology Clinic, US Naval Hospital, San Diego, Calif. A new observation is reported in five of these cases consisting of diffusion of red cells into the surrounding upper dermis creating a brown halo about the central black lesion. A representative case is presented.