Background: Nonalcoholic fatty liver disease (NAFLD) is among the most common causes of chronic liver disease and cirrhosis. In NAFLD, histological course of steatosis is usually macrovesicular (MacroS), but it may be accompanied by varying degrees of microvesicular steatosis (MicroS). Thus, in this study, we aimed to evaluate the prevalence and significance of MicroS in subjects with NAFLD.

Methods: A retrospective analysis of clinical and laboratory data of patients with histologically proven NAFLD was performed. The liver biopsy specimens which stained with hematoxylin eosin, reticulin, and Masson’s Trichrome stains were evaluated by single expert liver pathologist. Scoring and semiquantitative assessment of steatosis and NAFLD severity was done according to Kleiner scale known as NAFLD activity score (NAS). Grading for steatosis, steatosis type, zonal distribution of steatosis and other histological findings were also determined.

Results: The prevalence of MicroS among the study population (n= 191) was 30.4%. There was no difference regarding the demographic and biochemical parameters between patients with or without MicroS. On the other hand, the prevalence of ballooning injury and megamitochondria were higher in patients with MicroS (p= 0.019 and p= 0.036, respectively). There was a significant association of MicroS with ballooning injury (OR 2.65, 95% CI= 1.26-5.55; p= 0.005) and the presence of megamitochondria (OR 3.72, 95% CI= 1.00-13.72; p= 0.037).

Conclusion: MicroS is common in patients with NAFLD and is associated with early histological findings in this clinically relevant condition. Further longitudinal studies are needed to characterize the role of MicroS in the natural history of NAFLD.