Small hepatocellular carcinoma presenting with massive metastasis in the peritoneum, mimicking sarcomatous tumor

The case of a 51‐year‐old man with hepatitis C virus (HCV)‐related hepatocellular carcinoma metastasizing to the peritoneal cavity and mimicking a sarcomatous tumor is presented. A 12 × 12 cm mass, disclosed by computed tomography (CT), in the peritoneal cavity was predominantly isodense to muscle but had hypodense areas that suggested necrosis. T1‐weighted magnetic resonance imaging (MRI) showed a large mass, slightly hyperintense to muscle, with local hyperintense areas of suspected hemorrhagic necrosis.T2‐weighted MRI of the same region revealed a markedly non‐homogeneous and hyperintense mass with inner high signals and peripheral brush‐like linear striations. From such imaging studies, sarcomatous tumors, such as fibrosarcoma, leiomyosarcoma, and gastrointestinal stromal tumors, can be distinguished. Pathological findings at autopsy revealed necrotic tissue with a small portion of moderately differentiated HCC. Further studies may provide insights into the metastatic modes of HCC.