Microvesicular Steatosis in Individuals with Obesity: a Histological Marker of Non-alcoholic Fatty Liver Disease Severity

Background In non-alcoholic fatty liver disease (NAFLD), steatosis can manifest through two distinct forms: macrovesicular (macroS) and microvesicular (microS). Objective To investigate the prevalence of microS and its association with biochemical parameters and NAFLD-related histological findings in individuals with obesity. Methods This is an observational retrospective cross-sectional study, enrolling individuals who underwent bariatric surgery and liver biopsy at a university hospital. A 1:2 propensity matching was performed to pair microS with isolated macroS; this matching enrolled variables "age," "gender," "body mass index (BMI)," and "obesity-associated medical problems." Clinical, biochemical, and histopathological aspects were then analyzed and compared. Results Of 115 participants, 88.7% were female; average age was 40.5 +/- 5 years and mean BMI was 37.9 +/- 3.3 kg/m(2). Stea-tosis occurred in 82.6% (67.8% isolated macroS and 14.8% microS). MicroS is significantly associated with higher levels of alanine aminotransferase (ALT) (39.8 +/- 26.4 vs. 26.7 +/- 17.5; p = 0.04) and glucose (103.8 +/- 52.6 vs. 83.3 +/- 10.8; p = 0.03) and higher frequencies of moderate to severe macroS (41.2% vs. 2.0%; p < 0.001), portal fibrosis (100% vs. 50%; p < 0.001), perisinusoidal fibrosis (100% vs. 55.9%; p < 0.001), lobular inflammation (100% vs. 41.1%; p < 0.001), and portal inflam-mation (100% vs. 41.1%; p < 0.001). An independently positive association was observed between intensities of microS and macroS (p < 0.001). Conclusion MicroS is significantly associated with higher levels of ALT and glucose and higher frequencies of moderate to severe macroS, hepatocellular ballooning, portal fibrosis, perisinusoidal fibrosis, lobular inflammation, and portal inflam-mation. These findings indicate that microS could be considered a reliable histological marker of NAFLD severity.