Patients with conventional epithelioid hemangioendothelioma with WWTR1-CAMTA1 fusion had a less favorable outcome compared with the YAP1-TFE3 subset, the 5-year overall survival being 59% versus 86%, respectively.
A recurrent YAP1-TFE3 gene fusion has been identified in WWTR1-CAMTA1-negative epithelioid hemangioendotheliomas arising in soft tissue, bone, and lung, but not in liver.
EHEs have been characterized by tumor-specific WW domain-containing transcription regulator 1(WWTR1)-calmodulin-binding transcription activator 1 (CAMTA1) translocations, and recently, a novel Yes-associated protein 1 (YAP1)-transcription factor E3 (TFE3) gene fusion was identified in EHEs.
This study confirms the high incidence of WWTR1-CAMTA1 and YAP1-TFE3 rearrangements in EHE and indicates that the staining pattern for TFE3 IHC is critical for specificity.