Yellow bruises on the breasts are usually due to bleeding from the subcutaneous tissue. It may be due to trauma, coagulation disorders, and subcutaneous tissue infection. 1. Trauma: Breasts inadvertently subjected to collision or extrusion, will lead to bleeding of the subcutaneous tissue of the breast, the blood accumulates in the breast under the skin can not be discharged, it will form a bruise, with the passage of time, the bruise will gradually turn into a yellowish-blue color. 2. Coagulation disorders: patients with coagulation factor deficiencies or hemophilia will lead to coagulation disorders, which may cause bleeding in the subcutaneous tissues of the patient’s breasts, resulting in the formation of yellow bruises. 3. Subcutaneous tissue infection: Breast subcutaneous tissue infection will cause localized redness, hardness, heat, and at the same time there are symptoms such as pressure pain, due to inflammation stimulation may cause subcutaneous capillary rupture, causing subcutaneous bruising, infection in the recovery, will leave a yellow bruise at the breast skin. Yellow bruises on the breast may also be due to other reasons such as breast tumors, etc. Please go to the hospital in time for examination and treatment to avoid aggravation of the situation.