Epithelioid hemangioendothelioma

Epithelioid hemangioendothelioma (EHE) is a rare vascular tumor of intermediate malignant potential that arises from the endothelial cells lining blood vessels. It can occur in virtually any organ but most commonly affects the liver, lungs, bones, and soft tissues. EHE was first described by Weiss and Enzinger in 1982 and is classified as a borderline (uncertain behavior) neoplasm. The clinical course is highly variable, ranging from indolent tumors that remain stable for years to aggressive forms with widespread metastatic disease. A characteristic genetic hallmark of EHE is the WWTR1-CAMTA1 fusion gene, resulting from a t(1;3)(p36;q25) translocation, found in approximately 90% of cases. A smaller subset harbors a YAP1-TFE3 fusion. Symptoms depend on the organ involved. Hepatic EHE may present with right upper quadrant pain, hepatomegaly, weight loss, and jaundice. Pulmonary EHE can cause cough, dyspnea, chest pain, or hemoptysis, and may be discovered incidentally on imaging as multiple pulmonary nodules. Bone and soft tissue involvement may present as pain or a palpable mass. Some patients are asymptomatic at diagnosis, with the disease found incidentally during imaging for other reasons. Multifocal disease involving multiple organs is common and does not necessarily indicate metastatic spread, as it may represent multifocal primary disease. There is no universally established standard treatment for EHE. Management depends on the extent and location of disease and its clinical behavior. Surgical resection is the preferred approach for localized tumors. For unresectable or multifocal disease, a watch-and-wait strategy may be appropriate for indolent cases. Systemic therapies including antiangiogenic agents (such as bevacizumab and pazopanib), mTOR inhibitors (such as sirolimus), and conventional chemotherapy have been used with variable success. Liver transplantation has been performed in select cases of hepatic EHE with favorable outcomes. Interferon-alpha and thalidomide have also been reported in case series. Clinical trials are ongoing to identify more effective targeted therapies.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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