Periosteal epithelioid hemangioendothelioma with leptomeric fibrils

A case of recurrent periosteal epithelioid hemangioendothelioma of the right femur in a 66-year-old woman is reported. Microscopic examination showed epithelioid tumor cells with frequent intracytoplasmic vacuoles arranged in small nests or cords in hyalinized stroma. Immuno- and lectin-histochemical studies for factor VIII-related antigen and ulex europaeus I lectin indicated the endothelial nature of the tumor cells. Ultrastructurally, a few tumor cells contained leptomeric fibrils and crystalline filamentous aggregates in addition to showing certain features of endothelial cells. There seems to be no previous report of a vascular tumor containing leptomeric fibrils, which are often noted in normal striated muscle cells and their tumors. The bland appearance of the epithelioid tumor cells, poor vasoformative nature and prolonged clinical course differentiated this tumor from conventional angiosarcoma and so-called hemangioendothelioma of bone.