Teratomas are tumors that occur in germ cells and can develop in many parts of the body. For example, they can occur within the central nervous system, mediastinum, and pelvic cavity, with the latter being more common. On ultrasound, teratomas have typical features, mainly presenting as abnormal masses. These masses predominantly show mixed echogenicity, with strong echogenicity being more pronounced, appearing as strongly echogenic masses. The strong echogenicity primarily refers to contents including teeth, and also visible are areas of medium to low echogenicity, which are mainly composed of fat and hair. Benign teratomas have smooth borders, while malignant teratomas have irregular borders and are generally larger in size.