A hepatic malignant spindle-cell neoplasm of uncertain lineage clinically favoring sarcomatoid hepatocellular carcinoma: a case report.

Background: Sarcomatoid hepatocellular carcinoma (SHC) is an uncommon and aggressive variant of primary liver cancer. Its clinical and radiological features are often nonspecific, and it may mimic inflammatory liver lesions. Evidence for unresectable SHC is limited, so management is frequently individualized. Case Description: A 43-year-old man with chronic hepatitis B presented with recurrent right upper abdominal discomfort and 3 kg weight loss over 1 month. He was provisionally diagnosed with a hepatic abscess at an outside hospital, and percutaneous aspiration and drainage were performed; however, microbiological confirmation and detailed treatment records were unavailable. On admission, he had no fever or jaundice. C-reactive protein (CRP) was elevated, procalcitonin (PCT) was low, serum alpha-fetoprotein (AFP) remained below 12 ng/mL, and liver function was child-pugh class A. Contrast-enhanced computed tomography (CT) showed multiple right hepatic lesions with suspected invasion of adjacent portal vein branches. Magnetic resonance imaging (MRI) demonstrated an irregular heterogeneous mass measuring approximately 88×85 mm. Because the clinicoradiological pattern was not fully consistent with simple infection, ultrasound-guided biopsy was performed. Biopsy revealed a hepatic malignant spindle-cell tumor. The initial pathological report noted limited tissue volume and atypical immunohistochemical expression, making definitive subclassification difficult. After integrated clinicopathological review, the lesion was interpreted as a malignant spindle-cell tumor clinically favoring SHC. The unresectable tumor was treated with transarterial chemoembolization (TACE), hepatic arterial infusion chemotherapy (HAIC) with fluorouracil, leucovorin, and oxaliplatin (FOLFOX), lenvatinib 8 mg orally once daily, and tislelizumab 200 mg every 2 weeks. Adverse events were mainly nausea, vomiting, and right upper quadrant (RUQ) pain. Follow-up imaging showed reduction to approximately 70×58 mm and stable disease by response evaluation criteria in solid tumors (RECIST) 1.1. Conclusions: A hepatic malignant spindle-cell tumor clinically favoring SHC should be considered when a presumed liver abscess has atypical imaging findings, low infectious concordance, suspected vascular involvement, or poor diagnostic coherence. Early biopsy is critical. Multimodal therapy may be feasible in selected unresectable cases, but a single case cannot establish efficacy or define the contribution of each treatment component.