METASTATIC EPITHELIOID HEMANGIOENDOTHELIOMA IN A PLEURAL EFFUSION - DIAGNOSIS BY CYTOLOGY

Epithelioid hemangioendothelioma (EH) is a vascular neoplasm of uncert ain malignant potential. We report a 22-yr-old female with a primary m alignant EH of the iliac bone with adjacent soft tissue involvement wh ich, during its metastatic course, presented as a pleural effusion. Th e effusion was cellular with tumor cells present both singly and in cl usters. Distinguishing cytologic features included cytoplasmic vacuoli zation consistent with primitive intracytoplasmic lumen formation, var iability in cell size, biphasic cytoplasmic staining with Diff-Quik st ain, multinucleation, cell in cell engulfment, and multiple prominent nucleoli. Differential diagnosis based on morphology included malignan t mesothelioma and adenocarcinoma Immunocytochemical stains on the neo plastic cells were positive for Ulex Europaeus, Factor VIII-related an tigen, and CD34, reflecting vascular differentiation and confirming th e diagnosis of metastatic EH to the pleural cavity. (C) 1994 Wiley-Lis s, Inc.