Malignant vascular tumors of the liver: radiologic-pathologic correlation.

Although benign vascular tumors of the liver are extremely common (hemangioma is the most common), malignant vascular tumors of the liver are very rare. In the adult, these tumors are angiosarcoma, epithelioid hemangioendothelioma, and Kaposi sarcoma. All hepatic malignant vascular tumors share histologic characteristics, grow around and into vessels, and are grossly multifocal. They may be misdiagnosed histologically, particularly if only a biopsy sample is available. Although imaging findings are often non-specific, some features are suggestive or even characteristic of these neoplasms. Such features include previous exposure to thorium dioxide (Thorotrast) in cases of angiosarcoma, coalescence of multiple nodules into large peripheral masses in epithelioid hemangioendothelioma, and association between acquired immunodeficiency syndrome and cutaneous involvement in Kaposi sarcoma. Because hepatic malignant vascular tumors are often multiple, the main differential diagnosis is metastatic disease. There is no effective treatment for these tumors, and although survival time is variable, the prognosis is generally unfavorable.