OBJECTIVETo investigate the clinicopathologic characteristics of epithelioid hemangioendothelioma (EHE).

METHODSThirteen cases of EHE were analyzed by gross examination, light microscopy and immunohistochemical staining.

RESULTSThe patients included 6 males and 7 females. The age of patients ranged from 11 to 74 years (mean = 43 years). The tumors were located in soft tissue, liver, lung, mediastinum, sacrum, and pleura. The tumor cells were epithelioid, spindled or polygonal-shaped and exhibited cord-like or small nest growth pattern. Some tumor cells formed cytoplasmic vacuoles, which contained erythrocytes. The tumor cells showed abundant eosinophilic cytoplasm. The stroma varied from highly myxoid to hyaline. In 3 cases, the tumors contained areas with significant atypia, brisk mitotic activity and necrosis. Immunohistochemical study showed that the tumor cells were positive for CD31, ERG, FLI-1, CD34, factor VIII and CKpan to different extents. Follow-up information was available in 10 patients with duration ranging from 8 to 65 months. Seven patients were alive and three died.

CONCLUSIONSEHE is easily a rare maligant vascular tumor,occurs in many organs other than soft tissue.EHE is misdiagnosed as carcinoma for its significant epithelioid morphology. Recognizing its clinicopathologic characteristics and combined application of specific vascular endothelial immunohistochemical markers are important to avoid confusion with other lesions.