Epithelioid hemangioendothelioma of bone and soft tissue: a fine-needle aspiration biopsy study with histologic and immunohistochemical confirmation.

We retrospectively reviewed two fine-needle aspiration biopsy (FNAB) specimens from two patients with histologically confirmed epithelioid hemangioendothelioma (EH). Both patients were men, ages 79 and 39 years; their primary tumors arose in the soft tissues of the mediastinum and within the proximal tibia, respectively. The former patient had symptoms of superior vena cava syndrome; multicentric intraosseous lesions involved the proximal tibia of the latter patient. All cytologic smears were hypercellular and composed of mostly disassociated single cells and small aggregates of ovoid to polygonal-shaped epithelioid cells. Nuclei were variable, ranging from ovoid and reniform to round and polylobated and surrounded by an abundant amount of dense cytoplasm. Binucleated epithelioid neoplastic cells were frequent. Nuclear pleomorphism ranged from slight to moderate, and small solitary to multiple nucleoli were identified within the majority of tumor cells. Rare neoplastic cells with a single, sharply demarcated intracytoplasmic vacuole and intranuclear cytoplasmic pseudoinclusions were observed in the smears of one tumor. Metachromatic stromal fragments, probably representing hyalinized chondromyxoid stroma, were seen in the other tumor. Neither case was recognized initially on FNAB as EH. Immunohistochemically, sections from the surgical biopsy specimens of both cases showed diffuse and strong immunopositivity for the endothelial marker CD31. Although the cytomorphology of EH appears distinct, clinicoradiologic correlation is essential, and immunohistochemistry may be helpful to avoid misdiagnoses.