Hepatoblastoma presenting with focal nodular hyperplasia after treatment of neuroblastoma

Focal nodular hyperplasia (FNH) is a benign, poorly understood hepatic tumor that is rare in children. Although there is no evidence for malignant degeneration, FNH can occur adjacent to a malignancy. Here, the case of a 4-year-old boy with a hepatic mass and history of stage IV neuroblastoma is presented. Initial imaging and core-needle biopsy were consistent with FNH. However, after left lateral segmentectomy, pathologic examination revealed a malignant tumor most consistent with small cell undifferentiated hepatoblastoma as well as 3 foci of FNH in the surrounding parenchyma.