Histiocytoid hemangioma of the innominate vein

Primary malignancies originating in large veins are infrequent. Leiomyosarcomas and malignant vascular tumors have been occasionally reported. The recently described histiocytoid hemangioma has a predilection for medium-sized and large vessels. A case is reported of histiocytoid hemangioma arising in the innominate vein and presenting clinically as a mediastinal mass.