CAMTA-1 Expression in 24 Cases of Hepatic Epithelioid Hemangioendothelioma in a Single Institute: Diagnostic Utility for Differential Diagnosis from Hepatic Angiosarcoma
Epithelioid hemangio-endothelioma (EHE) of the liver is an uncommon vascular tumor with variable clinical courses ranging from stable disease to fatal outcome. EHE can mimic epithelioid angiosarcoma, which has a more aggressive behavior, especially in a small biopsy sample. EHEs are known to have the WWTR1-CAMTA1 fusion gene, and nuclear expression of CAMTA1 by immunohistochemistry (IHC) has been reported in about 90% of EHEs in multiple organs. Our study aimed to validate the diagnostic utility of CAMTA1 expression in EHEs, especially in the liver. IHC was performed using anti-CAMTA1 antibody in 34 tumors (24 hepatic EHEs and 10 angiosarcomas). In CAMTA1-negative EHEs, TFE3 IHC was performed. Of the 24 hepatic EHEs, 22 (91.6%) showed nuclear staining for CAMTA1. One of two CAMTA1-negative cases showed TFE3 positivity. The other case was negative for TFE3. Meanwhile, all 10 angiosarcoma cases had no CAMTA1 expression. CAMTA1 is a highly sensitive and specific marker for diagnosis of hepatic EHE. It is helpful for differentiation of hepatic EHE and angiosarcoma, especially in small biopsy samples.