[A clinicopathologic study on 9 cases of epithelioid hemangioendothelioma]

To study the clinicopathological features of epithelioid (histiocytoid) hemangioendothelioma (EHE).

9 cases of EHE were examined by light microscopy and immunohistochemistry, 1 case with ultrastructural observation.

The patients' age ranged from 16 to 47 years (mean 32 years). The lesions occurred in both sexes and presented at a variety of sites including head and facial area (4 cases), upper limbs (3 cases) and lower limbs (2 cases). The morphological characters were: (1) "epithelioid" or "histiocytoid" tumor cells; (2) rounded or polygonal tumor cells arranged in nests, cords and irregular patterns; (3) the tumor cells were embedded in myxoid or hyaline matrix; (4) primitive lumen formation within a single tumor cell (intracytoplasmic lumens); (5) lack of pleomorphism, mitotic activity and necrosis; (6) presence of spindle cell hemangioendothelioma in some cases; (7) osteoclast like giant cells scattered throughout the entire lesion were observed in one case. Immunohistochemistry studies on 7 cases found that tumor cells were positive for vimentin (7/7), factor VIII-RAg (5/7), CD31 (5/7), CD34 (5/7), cytokeratin (2/7), CD68 and alpha-AT (1/7). Ultrastructural study of 1 case demonstrated Weibel-Palade bodies and an abundance of intermediate filaments in the cytoplasm. The follow-up of 6 cases found that 3 cases developed local recurrences but none of them metastasized.

EHE is a distinctive low-grade sarcoma whose etiology remains unknown. Recognizing its morphological characters is important to avoid confusion with other similar lesions.