Abstract
Epithelioid hemangioendothelioma is a rare vascular tumor of borderline malignancy which is characterized by the presence of "epithelioid" or "histiocytoid" endothelial cells. Superficial and deep tumors have been recognized in the extremities, head, neck, chest, and mediastinum of adult patients. It may also occur as a primary tumor of liver, bone, and other visceral organs. Few effusion cytologic findings of epithelioid hemangioendothelioma have been reported. We report a case of composite epithelioid hemangioendothelioma with focal epithelioid angiosarcomatous areas of the iliac bone and adjacent soft tissue in a 38-year-old female, which, during its metastatic course, was presented as a pleural effusion. The effusion was cellular with epithelioid cells presenting both singly and in clusters. The tumor cells were round to ovoid shewing cytoplasmic vacuolization, variability in cell size, and prominent nucleoli. The effusion smears and cell block sections revealed strong positive staining for CD31 and vimentin, weak positive for CD34 and Factor VIII-related antigen, and negative for cytokeratin, CEA, and calretinin. The cytologic findings in this case were similar to that of metastatic adenocarcinoma or malignant mesothelioma. Therefore, immunocytochemical staining in smear and cell block is a helpful tool to differentiate malignant 'epithelioid' cells in effusion.