Hypoechogenicity is a term used in ultrasound imaging. The intensity of the echogenicity of an ultrasound examination can reflect the density of the tissues and organs being examined and whether the tissues are diseased through density. However, it is usually not possible to determine benignity or malignancy based on the level of echo alone, and more detailed examination is required. When the ultrasound passes through the tissue, the lower the echo indicates the lower density of the examined area relative to the normal tissue, and the ultrasound image will show a relatively darker area, and the low echo is less likely to exist as an occupying lesion, which is mostly seen in benign lesions, such as cysts and edema, but cannot exclude malignant lesions. It is also necessary to observe whether the lesion has clear borders, regular morphology, abundant surrounding blood flow, and whether calcification is present inside the mass. Benign nodules tend to have clear borders, regular morphology, less blood flow, no adhesion to other tissues, and an aspect ratio of less than 1. Malignant nodules tend to have unclear borders, abundant blood flow, bleeding or calcification, and an aspect ratio greater than 1. To further clarify the benignity and malignancy, enhanced CT and ultrasonography can be performed, and if necessary, puncture biopsy should be performed to clarify the benignity and malignancy of the mass.