S5838 A Rare and Diagnostically Challenging Case of Spindle Cell Liver Angiosarcoma

Introduction: Spindle cell hepatic angiosarcoma is a rare but highly aggressive tumor that accounts for less than 1% of primary hepatic malignancies. Risk factors include men >50 years old and exposure to arsenic and vinyl chloride. We present a diagnostically challenging rare case of hepatic angiosarcoma. Case Description/Methods: A 44-year-old woman with no significant comorbidities presented to the hospital with complaints of diffuse body aches and subjective fevers. Physical examination was notable for a protuberant and distended abdomen. Workup showed anemia, thrombocytopenia and mildly elevated liver function tests. Computed tomography (CT) abdomen/pelvis with contrast showed numerous hypo-enhancing masses throughout the liver (largest mass 2.1 cm) along with a large splenic mass measuring 3.9 cm, concerning for malignancy, as well as loculated ascites. A comprehensive malignancy workup was performed, including tumor markers, flow cytometry, ascitic cytology, and bone marrow biopsy which came back unremarkable. Multiple percutaneous ultrasound and CT-guided liver biopsies were also performed which were non-diagnostic, showing only benign parenchyma. Given the negative workup, she underwent laparoscopic liver biopsy, which showed proliferation of atypical, pleomorphic endothelial cells forming irregular vascular channels, positive for CD31 and CD34, consistent with high-grade spindle cell hepatic angiosarcoma. She was not a candidate for surgery or radiation therapy, given the metastatic nature of the disease, and was started on palliative pembrolizumab. She continued to have anemia and thrombocytopenia, requiring multiple blood product transfusions. Five days after starting immunotherapy, she was found to have intra-abdominal hematoma and hemoperitoneum, likely related to tumor invasion and severe thrombocytopenia, and unfortunately, succumbed to her illness. Discussion: Spindle cell hepatic angiosarcoma carries a very poor prognosis, with median survival less than 6 months and 1-year survival rates below 15% with or without therapy. While it usually occurs in older males with chemical exposure, our case is notable for a 44-year-old woman with no arsenic or vinyl chloride exposure. Diagnosis was challenging, requiring laparoscopic biopsy—an approach sometimes necessary when less invasive methods fail. This case highlights the diagnostic difficulty and aggressive course of hepatic angiosarcoma, especially in atypical patients without classic risk factors.