Hard lumps in the nipple may be associated with breast diseases such as plasma cell mastitis, intraductal papilloma, cystic hyperplasia of the breast, and breast cancer. 1. Plasma cell mastitis: It is common in non-lactating or menopausal women over 40 years old. When plasma cell mastitis occurs, the nipple may secrete brown or bloody overflow. At the same time, lumps may be palpable in the areola and nipple area. 2. Intramammary duct papilloma: It often occurs in women aged 40~50 years old. Usually they come to the clinic because their underwear is stained with blood crust or dirty liquid. The lesion mostly occurs in the nipple area, and when touching the breast, a lump can be felt in the nipple and under the areola. 3. Breast cystic hyperplasia: When breast cystic hyperplasia occurs, the nipple may secrete brown, colorless, bloody fluid. At the same time, a lump may be palpable in the nipple area or inside the breast. 4. Breast cancer: If the breast cancer lesion is close to the nipple area, a hard lump may be touched in the nipple area during the examination, and it may be accompanied by symptoms such as nipple inversion, bloody fluid discharge, and enlarged lymph nodes. When there is a hard lump in the nipple, vigilance must be raised, and it is recommended to go to the hospital as soon as possible to discharge other malignant conditions. At the same time, it facilitates targeted treatment.