Cytologic features of hepatic YAP1-TFE3 rearranged epithelioid hemangioendothelioma

Epithelioid hemangioendothelioma (EHE) is a rare vascular tumor of intermediate malignancy, often with indolent behavior. Though most cases have a characteristic WWTR1-CAMTA1 gene fusion, a subtype of EHE with YAP1-TFE3 fusions and a distinct morphology has recently been described histologically, but no cases of YAP1-TFE3 EHE have been described in the cytology literature. We herein report on a case of YAP1-TFE3 fusion associated EHE diagnosed on fine-needle aspiration and core biopsy of a liver mass in an 18-year-old male patient who presented with synchronous lung and liver involvement. We also discuss the differential diagnosis of EHE on cytology specimens.

Automated summary

Epithelioid hemangioendothelioma (EHE) is a rare vascular tumor with intermediate malignancy, often showing indolent behavior. While most cases exhibit the characteristic WWTR1-CAMTA1 gene fusion, a subtype with YAP1-TFE3 fusion and distinctive morphology has been recently described. This report presents a case of YAP1-TFE3 fusion-associated EHE diagnosed on liver mass fine-needle aspiration and core biopsy in an 18-year-old male with synchronous lung and liver involvement, discussing the differential diagnosis of EHE on cytology specimens.