Non-alcoholic fatty liver disease is a clinical syndrome characterized by hepatocellular steatosis and fat accumulation in the lobules of the liver without a history of excessive alcohol consumption, and includes three main types of fatty liver disease: simple fatty liver, steatohepatitis, and fatty cirrhosis. Patients are often associated with susceptibility factors such as overweight or obesity, abnormal glucose tolerance or type 2 diabetes, and dyslipidemia.
I. Clinical diagnosis criteria
Non-alcoholic fatty liver disease can be diagnosed when any of the following items 1 to 4 and 5 or 6 are present
1. No history of alcohol consumption or consumption of alcohol containing <40g of ethanol per week;
2.Excluding viral hepatitis, total parenteral nutrition and other specific diseases that can lead to fatty liver;
3, the onset of clinical manifestations, may appear weakness, abdominal distension, vague pain in the liver area and other symptoms, may be accompanied by hepatosplenomegaly;
4.Serum aminotransferase may be elevated, with alanine aminotransferase as the main enzyme, often accompanied by increased levels of γ-glutamyl transpeptidase, triacylglycerol, etc;
5.The liver imaging performance conforms to the diagnostic imaging criteria of diffuse fatty liver;
6.Hepatic histological changes conform to the pathological diagnostic criteria of fatty liver disease.
II. Clinical typing criteria
The clinical typing of those who meet the clinical diagnostic criteria of non-alcoholic fatty liver disease is as follows.
(A) Non-alcoholic simple fatty liver
Anyone who has any of the following items 1 to 2 and 3 or 4 can be diagnosed.
1.With clinical diagnostic criteria 1～3;
2.Liver function tests are basically normal;
3.Imaging performance meets the fatty liver diagnostic criteria;
4.Hepatic histological manifestations conform to the diagnostic criteria of simple fatty liver.
(B) Non-alcoholic steatohepatitis
Anyone who has any of the following items 1 to 2 and 3 or 4 can be diagnosed.
1, with clinical diagnostic criteria 1 to 3;
2.Serum ALT level is higher than 2 times the upper limit of normal value and lasts for more than 4 weeks;
3.Imaging performance meets the diagnostic criteria of fatty liver;
4, liver histological performance in line with the diagnostic criteria of steatohepatitis.
(C) Non-alcoholic fatty cirrhosis
Anyone who has any of the following items 1 and 2 or 3 can be diagnosed.
1.With clinical diagnostic criteria 1~3;
2.Imaging suggests fatty liver with cirrhosis;
3. Histological changes in the liver conform to the diagnostic criteria of fatty cirrhosis.
3.Imaging diagnosis
1.Fatty liver: ultrasound diagnosis is based on.
(1) Diffuse dotted hyperecho in the near field of the liver area, with higher echogenicity than that of the spleen and kidney, and a few focal hyperechoes;
(2) Far-field echogenic attenuation with sparse dots;
(3) Intrahepatic ductal structures are poorly visualized;
(The CT diagnosis is based on a generally lower density of the liver than the spleen or a liver/spleen CT ratio ≤ 1. A mild liver with a slightly lower CT value than the spleen and a liver/spleen CT ratio ≤ 1.0; a moderate liver with a liver/spleen CT ratio ≤ 0.7 and poorly visible intrahepatic vessels; a significantly lower density or even a negative liver with a liver/spleen CT ratio ≤ 0.5 and poorly visible intrahepatic vessels. Intrahepatic vessels are clearly visible as severe.
2. Cirrhosis: The imaging diagnosis is based on wide liver fissure grant, increased thickness of liver envelope, irregularity of liver surface, inhomogeneous echogenicity/density/signal in the liver, mismatch in the ratio of liver lobes, thickening of portal vein trunk diameter, increase of portal vein blood flow per minute parameter, increase of spleen volume index, thickening of gallbladder wall or change of gallbladder morphology, etc.
IV. Histological diagnosis
The pathological changes of non-alcoholic fatty liver disease are mainly large vesicular or large vesicular predominantly with small vesicular mixed hepatocellular steatosis, and the histological diagnosis can be divided into simple fatty liver, steatohepatitis, fatty liver fibrosis and liver cirrhosis.
1. The diagnosis of simple fatty liver is based on: steatosis of more than 30% of hepatocytes in the field of view under low magnification, but no other obvious histological changes, i.e. no inflammation, necrosis and fibrosis. A hepatocyte steatosis of 30% to 50% in the visual field is considered mild fatty liver; a hepatocyte steatosis of 50% to 75% is considered moderate fatty liver; a hepatocyte steatosis of 75% or more is considered severe fatty liver. The hepatocyte steatosis in the low magnification field of view <30% is called hepatocyte steatosis.
2, the diagnosis of steatohepatitis is based on.
(1) hepatocyte macrovesicularity or mixed steatosis with macrovesicularity as the main cause;
(2) ballooning of hepatocytes, even with varying degrees of hepatocyte necrosis;
(3) Mixed inflammatory cell infiltration in the lobules, or inflammation in the lobules heavier than in the confluent area.
3, fatty liver fibrosis and cirrhosis: according to the degree of fibrosis in hepatic alveolar zone 3, portal fibrosis, bridging fibrosis and the presence of cirrhosis fatty liver fibrosis is divided into 4 stages: S1 for focal or extensive perisinusoidal fibrosis in hepatic alveolar zone 3; S2 for the above lesions + focal or extensive perisinusoidal fibrosis; S3 for S2 lesions + focal or extensive bridging fibrosis; S4 for fatty cirrhosis with formation of fibrous septa dividing the hepatic lobules from the central vein to the portal area, forming pseudobullets. After the onset of cirrhosis, hepatocellular steatosis and inflammation may diminish and sometimes subside completely.