A case of pulmonary malignant epithelioid hemangioendothelioma misdiagnosed as adenocarcinoma by fine needle aspiration cytology.

Malignant epithelioid hemangioendothelioma (MEHE) is a rare vascular tumor with a biological behavior that lies between those of classical epithelioid hemangioendothelioma and angiosarcoma. Furthermore, MEHE is rarely diagnosed by fine needle aspiration cytology. The authors describe the cytological features of MEHE in a 41-year-old man who presented with increasing dyspnea over a period of 1 month before admission. Computed tomography of the chest showed a 3 cm poorly defined mass in the right lower lobe. Fine needle aspiration cytology demonstrated cellular smears of loosely cohesive clusters of epithelioid cells with numerous intracytoplasmic lumens in a necrotic background. Cellular features included fine chromatin and vesicular or slightly hyperchromatic nuclei with inconspicuous nucleoli and intranuclear inclusions. Nuclear membranes were relatively irregular with indentation. Mean N/C ratio was not increased, presumably due to a moderate amount of cytoplasm. The histologic examination displayed epithelioid and spindle cell proliferation with necrosis accompanying a classical epithelioid hemangioendotheliomatous area. The immunohistochemical evaluation was confirmatory and showed immunoreactivity for vascular markers. The authors also reviewed FNAB findings of epithelioid angiosarcoma, primary adenocarcinoma, and bronchioloalveolar carcinoma of the lung to identify cytomorphologic differences by literature bases. MEHE of the lung is difficult to diagnose cytologically because of its rarity and its cytomorphologic similarities with other malignant epithelial and mesenchymal tumors. However, it may be possible to distinguish it from other entities when the possibility of this unusual vascular neoplasm is suspected and ancillary studies are supportive.