Cytopathologic characteristics of epithelioid vascular malignancies

Objectives: Epithelioid hemangioendothelioma (EHE) and epithelioid angiosarcoma (EAS) are rare vascular neoplasms that share many morphological characteristics on histology but demonstrate different clinical behavior. Given the many reported clinical and morphological features shared between EAS and EHE, we examined all cases of EAS and EHE diagnosed primarily on fine needle aspiration (FNA) at our three institutions that were confirmed by a tissue diagnosis. Study Design: A total of 29 cases from 25 patients were identified: 15 EHE from 11 patients and 14 EAS from 14 patients. Results: Many cytomorphological features existed on a spectrum that overlapped considerably between EAS and EHE cases. Common features between the two entities include epithelioid morphology and eccentrically placed nucleus. Intracytoplasmic lumens (ICL), a morphological feature that may suggest vascular origin, can be found in both entities but are not always present. Conclusions: Given the general absence of vascular cytomorphological features, such as ICL, the proper classification of these tumors depends on the successful use of immunoperoxidase markers such as factor VIII-related antigen, ERG, or CD31 as well as a high index of suspicion. The distinction between EAS and EHE on FNA alone is treacherous at best.