The challenges of hepatic epithelioid hemangioendothelioma: the diagnosis and current treatments of a problematic tumor

Abstract

Background: Hepatic epithelioid hemangioendothelioma (HEHE) is a malignant vascular tumor known for its rarity. The different types of this hepatic tumor (single, multiple-nodular or diffused) indicate different prognosis and treatment plans. However, the heterogenic clinical manifestation creates a dilemma and a wide range of challenges when attending to HEHE patients. This review addresses the unique profile and clinical challenges that complicate the diagnosis and treatment of HEHE while focusing on current therapeutic strategies and their limitations.

Main text: The unclear etiology is a challenging feature of HEHE. The exact involvement of potential risk factors and mechanism of development are still undefined. Relevant genetic alterations like WWTR1-CAMTA1 fusion have been investigated; however, they are only applicable as diagnostic markers and their influence on therapeutic efficacy is largely unknown. Other characteristics include asymptomatic manifestation, lack of unique hepatic functional alterations, high rates of misdiagnosis and late-stage identification when metastases already exist. Currently, tissue biopsy is the main tool to establish a definite diagnosis but is challenged with the limited awareness to suspect HEHE at early stages and the lack of relevant guidelines due to the rarity and the insufficiency of relevant research. The absence of treatment guidelines is the greatest challenge of HEHE. Generally, Surgical approaches are recommended due to the benefits of prolonged survival and enhanced prognosis. Nonetheless, only a minority of patients are eligible for resections while liver transplants are faced with severe insufficiency of donor organs and long wait-lists. On the other hand, a variety of non-surgical treatments (like anti-angiogenic agents, interferon alpha-2B and sirolimus) are presented with a promising potential. However, relevant studies are challenged with limited sample-sizes and lack of prospective designs.

Conclusion: Regardless to decades passing since its discovery, HEHE still creates a dilemma due to its challenging clinical profile and lack of treatment guidelines. Raising awareness of HEHE in clinical practices improves the ability to diagnose this rare tumor at early stages and develop stronger research strategies and treatment guidelines to regulate the medical care provided to HEHE patients.

Keywords: Anti-angiogenesis; Hepatic epithelioid hemangioendothelioma; Interferon; Sirolimus; Surgery; WWTR1–CAMTA1 fusion.