Microvenular hemangioma: a clinicopathologic review of 13 cases.

Abstract

Microvenular hemangioma is an uncommon benign vascular tumor that can potentially be mistaken for malignancy. We reviewed the histopathologic and clinical features of 13 microvenular hemangiomas, which represents the largest series reported to date. The patients [female (F) = 8 and male (M) = 5] had a mean age of 39 years (range: 16 months-69 years). All presented with a similar history of a new, asymptomatic, stable or slow-growing, red to purple plaque or nodule. The lesions were located on the extremities, chest, back or abdomen. Two patients had multiple lesions. In six, a vascular tumor was not suspected clinically. Histologically, all were composed of a dermal proliferation of thin-walled, often branching, vascular channels dissecting through collagen fibers. The vessels were surrounded by a conspicuous layer of pericytes. Immunohistochemistry showed that all were positive for a vascular marker. Stains for WT-1 were positive in 9 of 10. None of the lesions tested (0/12) were positive for podoplanin or human herpesvirus-8 (HHV-8) (0/9). Follow-up available on six patients showed no recurrences. The histomorphology of microvenular hemangioma frequently raises concern for a malignant vascular lesion, especially Kaposi sarcoma. Identification of characteristic features, particularly the pericyte layer in routinely stained sections or with an SMA immunostain, allows an accurate diagnosis.