“Patchy slightly hypodense shadows with poorly defined borders are seen in segment S4 of the liver” is usually the term used in hepatobiliary ultrasound. Segment S4 of the liver is the left medial lobe of the liver, and patchy slightly hypodense shadows with poorly defined borders are seen, which may indicate the presence of localized benign lesions such as heterogeneous fatty liver, hepatic cysts or malignant lesions such as hepatocellular carcinoma. Slightly hypodense shadows in the liver can be seen in many ways. If the hypodense shadows are limited and patchy, they may be caused by benign lesions such as heterogeneous fatty liver, hepatic cysts, or intrahepatic hemangiomas. However, due to the “unclear border”, it may also be liver cancer or liver abscess, in which case further examination is needed to confirm the diagnosis. Since there are many causes of the patchy, slightly hypodense shadow with unclear borders in the left inner lobe of the liver, patients should undergo further examination under the guidance of their doctor for a clear diagnosis and treatment.