Solitary Muscle Metastasis of Hepatocellular Carcinoma to the Biceps Femoris Muscle with Only Elevated Serum PIVKA-II: A Case Report.

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.