Epithelioid Vascular Tumors of Bone and Soft Tissue

Endothelial cells distinguished by their epithelioid morphology have been recognized for many years. Rosai first characterized them as “histiocytoid” in appearance in 1979 and soon thereafter they became known by the more popularized term "epithelioid". By the early and mid 1980's this nomenclature was incorporated into classification schemes of epithelioid vascular tumors that included reactive, benign and malignant proliferations such as variants of bacillary angiomatosis, epithelioid hemangioma, spindle cell hemangioma, epithelioid hemangioendothelioma and epithelioid angiosarcoma. Subsequently, several new uncommon entities including composite hemangioendothelioma and epithelioid sarcoma-like hemangioendothelioma were described. As a group, these tumors can originate in a variety of different organ systems however, most develop in the soft tissues and skeleton. The epithelioid endothelial cell is common to them all, however, it is very important to distinguish amongst them as they have significant differences in their clinical behavior and biological potential and consequently their treatment and prognosis.