A case of progressive focal nodular hyperplasia developed in a young patient taking oral contraceptives

The patient was a 25-year-old woman. In January 2015, a 23-mm single nodule was found in segment 7 of the liver by ultrasonography. The size of the nodule increased to 52 mm in March 2017, and the patient underwent percutaneous liver biopsy. Focal nodular hyperplasia (FNH) was suspected from the biopsy, but hepatic adenoma (HA) was not ruled out. The nodule size continued to increase after the biopsy, and the patient was transferred to our hospital for consultation. FNH was suspected from the radiological study. However, HA was not excluded as a possibility because the patient had taken an oral contraceptive and the nodule continued to increase in size. An extended right posterior sectionectomy was performed to address the concerns of malignant transformation and bleeding. The final diagnosis from the histological analysis was FNH. Progressive FNH in a young woman taking oral contraceptives is very rare and has not been reported before.