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

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.

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.

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.

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