Nodular regenerative hyperplasia of the liver.

Nodular regenerative hyperplasia (NRH), characterized by diffuse hepatic micronodular transformation in groups without fibrous septa between the nodules, is a rare benign liver lesion that has many synonyms in previous literature. Pathologic evaluation is the mainstay of accurate diagnosis. Treatment is focused on its underlying conditions and complications of portal hypertension. A 39-year-old man visited our hospital due to right upper quadrant pain and a palpable liver mass. Magnetic resonance examination revealed a slightly hyperintense tumor on T2-weighted images, and focal nodular hyperplasia was diagnosed by the radiologists. Atypical radiologic findings could not yield an accurate diagnosis. Surgical intervention was therefore performed. Pathologic examination of the resected liver tumor confirmed the diagnosis of NRH. We conclude that NRH should be included in the differential diagnosis of benign liver tumor.