A case of small, single, and hypovascular hepatocellular carcinoma undiscovered until bone metastasis

A 71 year-old man with chronic hepatitis C under periodical medical check showed a gradual increase of serum AFP level despite negative imaging study results for any tumor in the liver. But, when he complained right thigh pain, CT images indicated a hypovascular nodule, 1 cm in size, in the Segment 8 of the liver, while MRI revealed metastatic bone lesions at right thigh. Then, he received radiation for the metastatic bone lesions. Three months later, he underwent the Kotz prosthesis operation due to bone fracture at the site, which provided histological diagnosis of the lesion as a moderately differentiated hepatocellular carcinoma (HCC). At that time, his hepatic nodule was still a small one without hypervascularity, while multiple lung metastases were already present. After 3 months, the hepatic nodule in Segment 8 advanced with portal vein tumor thrombosis, along with further elevations of AFP and PIVKA-II, and enlargement of lung metastases. Eventually he died of deterioration of general conditions due to progressive malignant lesions. Thus, here we report this rare case of a small, single, and hypovascular HCC, which showed peculiarly an early development of bone metastasis.