S5404 Rare but Real: Hepatic Epithelioid Hemangioendothelioma Uncovered Through Vague Abdominal Pain

Introduction: Hepatic epithelioid hemangioendothelioma (HEHE) is a rare vascular liver malignancy, comprising <1% of hepatic tumors, with a prevalence under 1 in 10 million. It affects all age groups, more commonly women, with a mean onset at 41.7 years. Diagnosis requires histopathology with immunohistochemical confirmation. Management varies based on disease burden, ranging from surveillance to liver transplantation. We present a case of multifocal HEHE in a young woman, highlighting individualized, multidisciplinary care. Case Description/Methods: A 29-year-old woman presented with intermittent abdominal discomfort. She denied systemic symptoms. Physical exam and labs, including liver enzymes, complete blood count, coagulation profile, and tumor markers (alpha-fetoprotein, carcinoembryonic antigen, CA 19-9), were normal. Ultrasound showed multiple hypoechoic liver lesions. Contrast-enhanced MRI revealed multifocal, peripheral-enhancing lesions with capsular retraction in both lobes. Differential included metastases, cholangiocarcinoma, or atypical infection. Liver biopsy showed epithelioid endothelial cells in fibromyxoid stroma with intracytoplasmic vacuoles. Immunohistochemistry was positive for CD31, CD34, and factor VIII, confirming HEHE. Positron emission tomography and computed tomography showed no extrahepatic spread or significant metabolic activity. Due to multifocal unresectable disease, liver transplantation was recommended. After obtaining a second opinion, the patient chose surveillance. She was counseled on systemic options, including mTOR inhibitors (e.g., sirolimus), vascular endothelial growth factor inhibitors (e.g., bevacizumab), and chemotherapy agents such as interferon-alpha, 5-FU, and doxorubicin, which show variable success in limited studies. At 12-month follow-up, she remained asymptomatic with stable imaging and normal liver function. Discussion: HEHE often presents incidentally or with vague symptoms. Imaging findings are suggestive but not specific; biopsy is essential for diagnosis. Treatment strategies range from liver transplantation and systemic therapies—including mTOR inhibitors, interferon-alpha, vascular endothelial growth factor inhibitors, and anthracycline-based chemotherapy—to surveillance in indolent cases. This case underscores the role of shared decision-making in managing this rare, unpredictable malignancy.