Background: Epithelioid hemangioendothelioma (EHE) is a rare neoplasm of vascular origin that occurs in the liver and other organs; its etiology is unknown.
Methods: The authors analyzed the clinicopathologic and immunohistochemical features of 137 patients with EHE of the liver in an attempt to identify features that might predict tumor behavior. To their knowledge, this article represents the largest series reported from one institution.
Results: Patients were ages 12-86 years; 84 (61%) were females and 53 (39%) were males. They presented with nonspecific symptoms such as right upper quadrant pain or weight loss. Macroscopically, the tumors usually were multiple. They typically were white, firm to hard, and ranged in size from 0.2-14 cm. Histologically, the tumors were comprised of dendritic and epithelioid cells that often contained vacuoles representing intracellular lumina. The stroma was fibrous, with myxohyaline areas. Immunohistochemically, all tumors were positive for at least one endothelial marker (factor VIII-related antigen [FVIII-RAg], CD34, and/or CD31). Treatment modalities included hepatic resection or transplantation. Although the metastatic rate in this series was 27%, the prognosis is considered much more favorable than that of other hepatic malignancies. Twenty-six patients (43%) survived > or = 5 years; 2 patients were alive and well at last follow-up after 23 and 27 years, respectively. Twenty-six of 60 patients (43%) died of their disease, 1 of whom died 28 years after discovery of her tumor. In an attempt to predict behavior of the tumor, several histologic parameters were evaluated using univariate analysis. No significant correlation was found with mitoses, Glisson's capsule infiltration, or nuclear atypia. High cellularity was significantly correlated with a poor clinical outcome (P = 0.00012), whereas the association with tumor necrosis approached significance (P = 0.057).
Conclusions: EHE is a very rare clinical entity. The key to diagnosis is the demonstration of cells containing FVIII-RAg. The histology of the tumor, including nuclear pleomorphism and the mitotic count, are of no value in predicting clinical outcome. High cellularity most likely is the most significant parameter predicting an unfavorable prognosis in EHE because mitotic counts often are quite low in both low grade and aggressive tumors. Further studies are needed to identify the factors responsible for the apparent dissociation between the clinical behavior and biologic characteristics of this tumor.