Focal Nodular Hyperplasia (FNH) of the Liver Following Treatment of Childhood Cancer

Purpose: The purpose of this case study is to describe three different patients with complicated malignancies in their past medical history who received the diagnosis of FNH. The report will highlight the clinical features of each case, describe the diagnostic modalities utilized and increase awareness of FNH as a long term sequela of chemotherapy and radiotherapy used to treat childhood cancers. Methods: Medical records of three patients treated at Cook Children’s Medical Center who were identified to have FNH were collected. Medical history, medications, clinician notes, imaging, surgical reports, and pathology reports were all reviewed systematically. A literature review was conducted using PubMed, Scopus and UpToDate. Results: Two of the three patients had been successfully treated for metastatic and recurrent Wilms’ tumors; the third had been successfully treated for embyronal rhabdomyosarcoma of the pelvis. All three patients required chemoradiation leading to extensive follow up for the long term side effects of their therapy. All three cases of FNH were found incidentally on imaging, which was either routine or based on symptoms unrelated to the liver. The lesions were first identified an average of 9 years after completion of cancer therapy. Two of the patients underwent surgical biopsy while the third was diagnosed based only on imaging. A watchful waiting approach was applied to all three children and they are all doing well without any hepatic complications, although the lesions often continue to increase in size slowly. Conclusions: The pathogenesis of FNH is thought to be due to a vascular insult leading to ischemia and subsequent remodeling of the hepatic tissue with reperfusion. It is commonly found in adult women on estrogen therapy. The exact mechanism of its development in children is unknown; however, there appears to be a correlation with a past medical history of childhood malignancy and chemoradiation therapy. It is possible to make the diagnosis based on imaging alone to avoid more invasive diagnostic procedures, if the lesions are characteristic and if they are not suspicious for metastatic or recurrent disease. A watchful waiting approach is recommended in all cases of focal nodular hyperplasia of the liver.