Primary peritoneal epithelioid hemangioendothelioma.

Epithelioid hemangioendothelioma is an uncommon malignant vascular tumor of intermediate grade that occurs in a variety of organs and soft tissues. Diagnosis of epithelioid hemangioendothelioma is often complicated by the rarity of the tumor, and because the tumor shares many morphologic features with other peritoneal neoplasms. This report presents 3 cases of epithelioid hemangioendotheliomas arising as primary tumors of the peritoneum and reviews 7 previously reported cases to establish the demographic, clinical, morphologic, immunohistochemical, and ultrastructural features of this neoplasm. These cases demonstrate that the light microscopic features are very similar to epithelioid hemangioendothelioma arising at more conventional sites, such as the liver, that immunohistochemical analysis provides a reliable approach for confirming or establishing the diagnosis, and that at least one endothelial marker (either CD31, CD34, or factor VIII) should be positive for a definitive diagnosis. This series identifies the characteristics of peritoneal epithelioid hemangioendothelioma that can be reliably used for diagnosis.