S5556 Unexpected Detection of Primary Hepatic Angiosarcoma in a Car Mechanic With Ulcerative Colitis

Introduction: Angiosarcomas are rare soft-tissue sarcomas of endothelial cell origin that have a poor prognosis. Primary hepatic angiosarcoma (HA) accounts for approximately 2% of all liver tumors, yet it is considered the third most common primary hepatic malignancy, following hepatocellular carcinoma and cholangiocarcinoma. This case highlights an unexpected diagnosis of primary HA in a patient with ulcerative colitis and potential vinyl chloride exposure through occupational work as a car mechanic. Case Description/Methods: A 60-year-old man with ulcerative colitis (UC) presented with 2 months of right upper quadrant (RUQ) abdominal pain and jaundice. Physical exam was notable for jaundice, abdominal distension with RUQ tenderness, and prominent hepatomegaly. Lab results showed hemoglobin 7.8 g/dL, platelets 201 K/u, total bilirubin 10.3 mg/dL and direct bilirubin 7.9 mg/dL. Magnetic resonance imaging with and without contrast showed an enlarged liver mass with diffusely infiltrative process with countless lesions ranging from 1 cm to 10 cm. Ultimately, liver biopsy revealed HA. Given patient’s aggressive tumor burden, hospice care was recommended. Discussion: HA has a nonspecific presentation including abdominal pain, weight loss, and fatigue with a rapid progression of disease. It is linked to toxins like vinyl chloride and steroids, but most cases lack clear causes. Indirect exposure (e.g., PVC in automechanics) may pose risks. Although UC is associated to some liver cancers, no clear connection to HA has been identified. The most common laboratory abnormalities include anemia and thrombocytopenia, which are thought to result from the consumption of clotting factors. Abdominal imaging in HA typically shows multiple heterogeneous masses with hemorrhage, necrosis, or cavitation, often invading liver parenchyma, vessels, and nearby structures. Diagnosis relies on histopathology and immunohistochemistry, with biopsy showing epithelioid to spindled neoplasms and varied vascular patterns. Given its rarity and poor prognosis (median survival 6–12 months), HA lacks standardized management guidelines. Surgical resection may be possible if localized and liver function is preserved, though it is often limited by vascular invasion. Chemotherapy responses are typically limited and non-curative. Early diagnosis is crucial, and further research is needed to establish standardized diagnostic and management guidelines.