Transitional features of histologic type of non-alcoholic fatty liver disease in Korean young men

Background and Aim: The prevalence of non‐alcoholic fatty liver disease (NAFLD) is increasing in Korea as the dietary pattern and lifestyle become more Westernized and the obese population increases. The spectrum of NAFLD ranges from asymptomatic steatosis to non‐alcoholic steatohepatitis (NASH) and cirrhosis. Schwimmer et al. divided NASH into three types according to the histological characteristics, such as adult type, pediatric type and overlap type. We investigated clinical and histologic features of NAFLD patients in Korean young men. Methods: A total of 64 male patients under age 30 years, diagnosed as NAFLD by a liver biopsy, were reviewed retrospectively. NASH was diagnosed by NAFLD activity score (NAS), and NASH patients were classified with Schwimmer's histological classification. Results: Pathological features of liver biopsy revealed NASH in most cases (59 cases, 92.2%) including 29 cases (45.3%) of borderline NASH and 30 cases (46.9%) of definite NASH. The definite NASH group showed significantly high aspartate aminotransferase/alanine aminotransferase levels compared to the borderline NASH group. There were four cases (6.8%) of pediatric type, 17 cases (28.8%) of adult type, and 38 cases (64.4%) of overlap type in the NASH group. NAS was 3.75 ± 0.05 in the pediatric type, 4.29 ± 1.16 in the adult type and 4.87 ± 1.21 in the overlap type, and the overlap type showed a higher NAS than the pediatric type. The fibrosis stage was significantly higher in the overlap type than the other types. Conclusion: Most Korean young men with NAFLD turned out to have borderline or definite NASH. More than half of the NASH cases showed overlap type in Korean young men.