BACKGROUND: Hepatocellular carcinoma (HCC) is a common primary hepatic cancer. Regardless of its metastatic potential, metastasis to skeletal muscle is rare, especially to one solitary muscle. The diagnostic efficiency of Protein induced by Vitamin K absence/antagonist-II (PIVKA-II) has been illustrated sufficiently and it has been proven that PIVKA-II is a potent biomarker and independent of alpha-fetoprotein (AFP). The present report describes a case of solitary muscle metastasis with PIVKA-II elevation.

CASE REPORT: An 81-year-old man noticed a growing mass in the proximal posterior thigh, and it was found to be a solitary tumor in the biceps femoris muscle. He had undergone a medial segmentectomy for primary HCC and transcatheter arterial chemoembolization for an intrahepatic recurrence 7 and 4 years before, respectively. The level of PIVKA-II was elevated to 11 400 mAU/mL, but the alpha-fetoprotein (AFP) level was normal. Elevation of PIVKA-II to over 50 mAU/mL had been observed 7 months before the muscular lesion was first observed. When the solitary metastasis was diagnosed, a wide resection was performed in the same way as for primary sarcoma, and the PIVKA-II value decreased to 71 mAU/mL. No recurrence at the muscle was observed, but multiple lung metastases were seen and the PIVKA-II was elevated to 1410 mAU/mL 4 months after the resection.

CONCLUSIONS: Resection of the solitary muscle metastasis helped control the local metastatic lesion and helped with ability to perform daily activities, as well as possibly prolonging survival. PIVKA-II is an important biomarker for HCC surveillance in conjunction with alpha-fetoprotein (AFP). PIVKA-II can be independent of AFP. Examination of the whole body is still necessary in cases with elevated PIVKA-II in order to detect extrahepatic metastasis.

Keywords: Carcinoma, Hepatocellular, Magnetic Resonance Imaging, Aged, 80 and over, Hamstring Muscles, Liver Neoplasms, Muscle Neoplasms, Protein Precursors, Prothrombin