Hemangioendothelioma of the spleen.

Hemangioendotheliomas of the spleen are rare and are considered to be of intermediate/borderline malignancy. We report such a case in a patient who presented with chronic anemia but who otherwise was asymptomatic. The tumor involved half the organ and was solitary and nonencapsulated. Microscopically, it was composed of vascular and stromal elements. Both types of elements showed moderate atypia and rare mitoses. The lining cells stained positively with antibodies to factor VIII-related antigen and Ulex europaeus lectin. The stromal component showed evidence of myofibroblastic differentiation. One year after splenectomy, all hematologic parameters slowly improved and returned to normal. The clinicopathologic differences between hemangioma, angiosarcoma, and hemangioendothelioma are discussed, and cases that have recently been reported in the literature are reviewed.