Pathophysiology and development of non-alcoholic fatty liver disease, with associated risk factors. Histopathological lesions of NAFLD have been graded and staged regarding steatosis, steatohepatitis and fibrosis (, adapted from Brunt et al.).
*Grading for steatosis. According to percentage of affected hepatocytes: grade 1 (< 33%), grade 2 (33–66%), and grade 3 (> 66%).
**Grading for steatohepatitis: grade 1 or mild (macrovesicular steatosis, up to 66% of lobules; occasional ballooning; mainly scattered acute lobular inflammation; none or mild portal inflammation), grade 2 or moderate (mixed macrovesicular and microvesicular steatosis; obvious ballooning; possible mild chronic lobular inflammation; pericellular fibrosis; mild to moderate portal inflammation), and grade 3 or severe (> 66% of lobules affected by steatosis; marked ballooning; scattered acute and chronic lobular inflammation; perisinusoidal fibrosis; mild to moderate portal inflammation).
***Staging for fibrosis: stage 1 (focal or extensive, perivenular, perisinusoidal, or pericellular), stage 2 (with added focal or extensive periportal fibrosis), stage 3 (focal or extensive bridging fibrosis), and stage 4 (cirrhosis). HCC, hepatocellular carcinoma; TNF-α, tumor necrosis factor α; IL-6, interleukin 6; LDL, low-density lipoprotein