Nodular Regenerative Hyperplasia Is a Frequent Finding in Explanted Livers of Patients With Maple Syrup Urine Disease.

Background: Maple syrup urine disease (MSUD) is an autosomal recessive inherited disorder characterized by deficiency of branched-chain α-keto acid dehydrogenase complex. The affected patients can experience severe metabolic intoxication and encephalopathy in the first few years of life. Liver transplantation is an effective long-term treatment. There has been a lack of histologic description of explanted livers from MSUD patients in the literature.

Methods: A search of the medical record system was performed for cases carrying a diagnosis of MSUD between January 2003 and May 2024. Eight patients who underwent liver transplantation were identified. Their explanted livers were evaluated and their medical records were extensively reviewed.

Results: The weights of explanted livers were within normal range for patients' age. Histologic examination demonstrated features of nodular regenerative hyperplasia (NRH) in 5 (62.5%) liver explants. Other histologic findings included minimal to mild lymphocytic portal inflammation seen in 6 cases and mild steatosis in 2 cases. A detailed review of clinical histories revealed no signs of portal hypertension or specific underlying conditions conducive to NRH development.

Conclusion: NRH is a frequent histologic finding in explanted livers from MSUD patients, although the underlying etiopathogenesis and clinical implication remain to be elucidated.