A hard lump under the nipple that is red and peeling may be due to mastitis, breast hyperplasia, and subcutaneous soft tissue infection. 1. Mastitis: Mastitis in the early stages of the disease will appear breast swelling, pain, redness and swelling, with the development of the disease, the patient’s breasts will appear lumps. The actual fact is that it is a very good idea to have a good deal more than just a few of them. 2. Mammary hyperplasia: Mammary hyperplasia will lead to breast pain, redness and swelling, and the pain will be aggravated during menstruation. Patients may also develop breast nodules, leading to the symptom of hard lumps in the breasts. As the condition worsens, patients may experience nipple discharge and skin ulceration. 3. Subcutaneous soft tissue infection: Subcutaneous tissue infection will cause the patient’s local skin to appear red, hot, itchy, swollen symptoms, due to the stimulation of subcutaneous inflammation will lead to local hard lumps, peeling skin. At the same time, eczema of the skin around the nipple, plasma cell mastitis, eczema-like carcinoma of the mammary gland will also appear the symptoms of hard lumps under the nipple with redness and peeling skin. There are many reasons that lead to hard lumps under the nipple with redness and peeling, so it is recommended that patients consult with regular hospitals in a timely manner and standardize the treatment under the guidance of doctors.