Cytologic Features of Epithelioid Hemangioendothelioma

To determine cytologic features of epithelioid hemangioendothelioma (EHE) that would enable accurate diagnosis, we evaluated fine-needle aspiration biopsy (FNAB) smears from 11 histologically confirmed EHEs. The variably cellular smears comprised dispersed single cells and occasional cell aggregates. Dense stromal fragments were present in association with some tissue fragments. The cells were epithelioid, containing moderate or large amounts of dense cytoplasm. Nuclei exhibited mild pleomorphism, and nuclear grooves were identified in all cases. At least occasional intranuclear pseudoinclusions (INPIs) and intracytoplasmic lumina (ICLs) were present in all cases and in 9 cases (82%), respectively, and rare erythrocytes were seen within ICLs in 5 cases (45%). Mitotic figures were identified in 4 cases (36%). The background was bloody in 6 cases (55%) and contained hemosiderin and/or hemosiderin-laden macrophages in 5 cases (45%). The combination of the following features in FNAB samples should raise strong suspicion for EHE: predominantly dispersed single cells with occasional cohesive cell clusters; epithelioid cytomorphology; dense cytoplasm with well-defined cytoplasmic borders; ICLs (with or without erythrocytes), INPIs, and nuclear grooves. The presence of these features should prompt correlation with clinical, radiologic, and histologic features and immunohistochemical evaluation using vascular markers.