Morphological basis for the assessment of steatosis, steatohepatitis and fibrosis in patients with non-alcoholic fatty liver disease associated with obesity and pathology of the biliary tract

Background. The purpose was to study the histopathological features of steatosis, steatohepatitis and liver fibrosis in fatty liver disease of non-alcoholic etiology and to establish the linkages between the degree of steatosis, histological markers of fibrosis and increase of body mass index (BMI) in patients with non-alcoholic hepatic steatosis (NAHS) and non-alcoholic steatohepatitis (NASH) associated with obesity and pathology of the biliary tract. Materials and methods. The study included 70 patients with non-alcoholic fatty liver disease (NAFLD), including 48 individuals with NAHS combined with obesity (group 1), and 22 patients with NASH and obesity (group 2). Depending on the degree of increase in BMI, patients with NAHS, NASH and associated obesity were divided into three groups: BMI 25–29.9 kg/m2 — overweight; BMI 30–34.9 kg/m2 — I degree obesity; BMI 35–39.9 kg/m2 — II degree obesity. For histological diagnosis of NAHS/NASH, as well as to determine the stage of liver fibrosis, we used МЕТАVIR and BRUNT criteria. Results. The dependence of the severity of hepatic steatosis on BMI was detected in patients with different clinical forms of fatty liver disease, which was confirmed by the results of correlation analysis: NAHS — rs = 0.798 (p < 0.001), NASH — rs = 0.678 (p < 0.001). With increasing BMI, fibrous processes are exacerbated, from the presence of F0 stage in overweight patients with NAHS to F3 stage in II degree obesity in patients with NASH. The coefficients of correlation between BMI and the stage of liver fibrosis are: in NAHS — rs = 0.464 (p < 0.001), in NASH — rs = 0.759 (p < 0.001). Conclusions. In most cases of NAHS (58.3 %) and NASH (45.4 %,) macrovesicular steatosis was identified. Patients with NAHS more often had F1 and F2 fibrosis stages (50.0 %), while patients with NASH — F2 and F3 stages of fibrosis (77.3 %). Mixed type of liver fibrosis is characteristic of the comorbid course of NAFLD