Hypodense shadows in the left outer lobe of the liver may be due to hepatic cysts, malignant tumors in the liver, and hemangiomas of the liver. 1. Hepatic cyst: dilatation of the bile ducts caused by congenital dysplasia, characterized by low-density shadows and smooth edges. 2. Malignant tumors in the liver: chronic viral hepatitis, alcoholic cirrhosis caused by long-term alcohol consumption, and long-term consumption of moldy food can lead to the appearance of malignant tumors. Low-density shadow with blurred boundary will appear in the liver. 3. Hemangioma of the liver: this is a kind of benign liver tumor, caused by malformation of blood vessels around the liver, and is also a kind of developmental abnormality. It may be related to heredity and other factors, and appears as a low-density shadow in the left lobe of the liver. The appearance of low-density shadow in the left outer lobe of the liver should immediately go to the hospital to improve the relevant examination under the professional guidance of the doctor and standardize the treatment.