Mediastinal epithelioid hemangioendothelioma metastatic to lymph nodes and pleural fluid: report of a case.

Epithelioid hemangioendothelioma is a rare mesenchymal tumor of vascular origin, classified as a sarcoma of intermediate malignant potential. Involvement of numerous sites of the body, including visceral organs, soft tissue, testis, skeleton, brain, meninges, and skin have been described. We report an unusual case of a mediastinal epithelioid hemangioendothelioma in a 65-year-old female initially presenting as a metastasis to lymph nodes of the hilar region and subsequently as a malignant pleural effusion. The patient had a complex history of papillary renal cell carcinoma, papillary thyroid carcinoma, and Waldenstrom's hyperglobulinemia making the diagnosis of metastatic epithelioid hemangioendothelioma difficult. Clinical, cytological and immunohistochemical features of this tumor are described with an emphasis on diagnostic pitfalls.