Background: Focal nodular hyperplasia (FNH) is a benign hepatic tumor of unknown origin. It is only observed rarely in children (approximately 1-2% of all pediatric liver tumors).
Case report: A 12-year-old boy who suffered from infectious mononucleosis with liver involvement and hepatomegaly underwent a sonographic scan of the liver at an external hospital 3 months after the infection disappeared which revealed a tumor of the left hepatic lobule. Subsequent further examination (abdominal CT and MRT scans) confirmed the diagnosis of a highly vascularized mass about 10 cm in diameter, suspicious for FNH. Due to the high vascularization no biopsy was performed. A preoperative angiographic coiling and complete surgical resection was carried out because of the size and morphologic uncertainty. The diagnosis of FNH was confirmed by histological examination. The annual sonographic examination at follow-up has been uneventful for a 4-year period.
Conclusions: Due to the rarity the diagnosis of FNH in children can be difficult leading to differential diagnostic problems. Due to the risk of bleeding in larger size tumors a biopsy is a point of controversy. Complete resection and histopathological examination of FNHs in childhood is a mandatory therapeutic option, which may be indicated in large tumors or, as in the present case tumors of uncertain biological behaviour.