When a suspicious liver lesion is not cancer: primary hepatic myopericytoma in chronic hepatitis B

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A 47-year-old woman was found to have a 25 mm × 19 mm mass in hepatic segment VI. Serum alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA19-9), and protein induced by vitamin K absence or antagonist-II (PIVKA-II) levels were normal.Magnetic resonance imaging showed slight T1 hypointensity, T2 hyperintensity, arterial patchy enhancement, and progressive portal venous and delayed enhancement.18 F-fluorodeoxyglucose ( 18 F-FDG) positron emission tomography/computed tomography (PET/CT) showed increased uptake in the lesion, with a maximum standardized uptake value (SUVmax) of 7.7, and no abnormal uptake elsewhere.She had chronic hepatitis B virus infection, with positive hepatitis B surface antigen (HBsAg), hepatitis B e antibody (HBeAb), and hepatitis B core antibody (HBcAb).Because malignancy was suspected, laparoscopic right posterior sectionectomy, cholecystectomy, and hilar lymph node dissection were performed.Histopathology established the diagnosis of hepatic myopericytoma (MPC).Hematoxylin and eosin staining showed a well-circumscribed tumor composed of bland spindle-to-epithelioid cells with eosinophilic cytoplasm, arranged in a characteristic concentric perivascular pattern around thin-walled branching vessels.Immunohistochemistry showed positivity for smooth muscle actin and vimentin, partial desmin expression, vascular CD34 staining, and a Ki-67 labeling index of approximately 2% (Figure 1).The background liver showed mild chronic inflammation and steatosis, without acute hepatitis or cirrhosis.Primary hepatic MPC is exceedingly rare, with only six cases reported to date (1).Reported hepatic MPCs may show progressive enhancement and increased 18 F-FDG uptake, mimicking intrahepatic cholangiocarcinoma, perivascular epithelioid cell tumor, or hepatocellular adenoma (2,3).In this case, the concentric perivascular growth pattern and myoid immunophenotype supported the diagnosis.Complete surgical excision is the main treatment, and recurrence appears uncommon (4).This case is notable for the rarity of primary hepatic MPC and its occurrence in chronic hepatitis B virus infection.