Hepatic focal nodular hyperplasia in children previously treated for a solid tumor: Incidence, risk factors, and outcome

The detection of hepatic nodules, particularly in patients treated for a previous malignancy, raises a diagnostic dilemma. Focal nodular hyperplasia (FNH) of the liver is an uncommon, benign tumor in children and must be differentiated from malignant hepatic lesions. The etiology of FNH is obscure, and its pathogenesis is poorly understood. FNH may be a reaction to localized vascular abnormalities and circulatory disturbances. The goal of the current study was to identify risk factors for the occurrence of FNH in children who had received prior treatment for a malignant tumor. The current retrospective study examined 14 cases of FNH in pediatric patients who previously had been treated for a malignancy. Diagnosis was based on clinical and radiologic findings and was proven histologically in four cases. FNH lesions were discovered by chance during routine examination in 78% of patients. The incidence of FNH was particularly high in the current series (0.45%) compared with the incidence in the general pediatric population. High doses of alkylating agents (e.g., busulfan or melphalan), venoocclusive disease, and liver radiotherapy may be responsible for injury to the vascular endothelium and subsequent localized circulatory disturbances. FNH is characterized by the absence of complications after its detection; therefore, only close follow-up is recommended. FNH appears to be a late complication of an iatrogenic vascular disease in children with a history of malignancy.