Swelling of the superior sternal fossa is often associated with the following causes: 1. There may be a subcutaneous hematoma, which is often seen with a direct violent blow to the area. In this case, the local subcutaneous bleeding is very high and a hematoma is formed. 2. It may be caused by an old injury. For example, if the patient has a previous sternal fracture or soft tissue blunt contusion, then after recovery, there may be swelling due to the proliferation of bone scabs or the formation of scarring or adhesions. 3. It may also be caused by enlargement of the thyroid gland. If a patient has a simple goiter, Hashimoto’s disease, or thyroid cancer, the swelling may be present. 4. It may also be caused by gonorrhea of the neck. This disease is often caused by inflammation or infection around the neck, or metastasis of tumors such as breast cancer or lymphoma.