The mTOR pathway inhibition with everolimus in pseudomyogenic hemangioendothelioma harboring SERPINE1-FOSB gene fusion: a case report and review of the literature.

Pseudomyogenic hemangioendothelioma (PHE) is an extremely rare tumor that is frequently misdiagnosed as other vascular or soft tissue neoplasms and typically follows an indolent course. Due to its locally aggressive and multifocal nature, surgical intervention is often not feasible. Moreover, conventional chemotherapy has shown limited efficacy according to existing literature. Recent advances in genetic profiling have identified a SERPINE1/FOSB gene fusion in PHE, leading to the activation of the mechanistic target of rapamycin (mTOR) pathway. This discovery has highlighted mTOR inhibitors and multityrosine kinase inhibitors as promising therapeutic options. In this report, we present a PHE case with confirmed SERPINE1/FOSB fusion who was initiated on everolimus therapy, along with a review of the current literature.