Soybean-sized lumps in the paratesticular breasts may be related to paratesticular breast hyperplasia, paratesticular breast cancer, lymphadenitis and other causes. 1. Paramastomal hyperplasia: Paramastomal hyperplasia is caused by the imbalance of estrogen-progestin ratio and other reasons, which may cause pain and other symptoms, mostly related to menstrual cycle. 2. Breast cancer of the paratesticular breast: usually the first to appear as an axillary mass, most of which are painless lumps under the armpit or in front of the armpit. 3. Lymphadenitis: due to mastitis and other reasons, pathogenic bacteria invade the lymph nodes, which can cause lymph node enlargement, manifested as soybean-sized lumps in the paratesticular breast. It is recommended that people with soybean-sized lumps in the breasts go to the hospital in time to clarify the cause of the disease and carry out standardized treatment under the guidance of the doctor, so as to avoid delaying the condition.