Small lumps on top of breast nodules are irregularly shaped breast nodules, which may be due to mastitis, breast hyperplasia and breast cancer. 1. Mastitis: Mastitis is clinically classified as non-lactating mastitis and lactating mastitis. Lactating mastitis causes localized pain, heat, and swelling in the breast, accompanied by breast nodules. Non-lactating mastitis usually results in nipple discharge, breast pain, nipple inversion and breast nodules. 2. Mammary gland hyperplasia: Mammary gland hyperplasia often occurs in women around 30~50 years old, and this disease is related to endocrine dysfunction. In the early stage of the disease, it will cause bilateral or unilateral breast swelling and pain, and with the development of the disease, it may cause nipple discharge, breast pain and breast lumps or nodules. 3. Breast cancer: Breast nodules caused by breast cancer are usually characterized by rough surface, hard texture and unclear boundary, leading to the symptom of small lumps on the nodules. Malignant breast nodules usually have incomplete envelope and irregular shape. It is recommended that patients with lumps on breast nodules should consult regular hospitals in a timely manner and receive standardized treatment under the guidance of doctors after a clear diagnosis.