EPITHELIOID HEMANGIOMA OF BONE - A TUMOR OFTEN MISTAKEN FOR LOW-GRADEANGIOSARCOMA OR MALIGNANT HEMANGIOENDOTHELIOMA

Epithelioid hemangiomas are benign vascular tumors that usually occur in the skin and subcutis. They have been infrequently recognized in bo ne. Because of their unusual cytologic appearance and growth patterns, they are commonly confused with malignant tumors. We report a series of 12 epithelioid hemangiomas of bone occurring in adult patients, inc luding five males and seven females whose ages at presentation ranged from 24 to 74 years, with a mean of 46 years. Five tumors were associa ted with involvement of the adjacent soft tissue. A single patient had multifocal bone disease. The most common presenting symptom was local ized pain. Treatment of the patients varied widely; however, none of t he tumors behaved aggressively. In 11 cases, adequate tissue was avail able for immunohistochemical analysis, which revealed positive stainin g for the epithelial markers cytokeratin and epithelial membrane antig en in nine cases. All 11 tumors stained for factor VIII-related antige n and Ulex europeus agglutinin. We believe that many of the vascular t umors of bone that have been reported as low-grade malignant hemangioe ndotheliomas probably represent examples of epithelioid hemangiomas. W e recommend that the criteria for diagnosing vascular tumors of bone c onform to those used for morphologically similar tumors that arise in the soft tissues.