Occasional hard and itchy nipples may be caused by sebaceous cysts, breast hyperplasia, benign mammary nodules, mastitis and so on. 1. Sebaceous cysts: blockage of sebaceous ducts in the chest can lead to the accumulation of large amounts of sebum and the formation of cysts, which can irritate the local skin and cause hard and itchy sensations in the nipples. 2. Mammary gland hyperplasia: when the hormone level in the body changes, it will stimulate the mammary tissue and make the mammary gland hyperplasia which may cause hard and itchy nipple. 3. Benign breast nodules: If fibroids and other benign nodules occur in the breast, they can irritate the breast and the surrounding skin, causing a hard and itchy sensation. 4. Mastitis: When inflammation occurs in the mammary glands, it will irritate the surrounding tissues and skin and cause itchy and hard feelings in the nipples. When hard, itchy sensations persist in the nipples of the body, it is important to pay attention to them and consult a doctor in time to clarify the cause and treatment.