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 x 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.