Male nipple enlargement is most often seen in gynecomastia, which commonly occurs during puberty and old age. It is a hyperplastic enlargement of the mammary glands caused by excessive estrogen production or a decrease in the ratio of androgens to estrogen, and is accompanied by an enlarged nipple and areola area. There are no characteristic clinical manifestations, but hyperplastic nodules can be palpated in the subareolar area and are associated with pain and swelling. In the case of breast development in old age, oral triamcinolone can be used as anti-estrogen therapy to prevent further progression of the disease when the hyperplasia is not obvious and the symptoms are mild. When breast development is obvious, surgical treatment is required, most of which is mastectomy. In daily life, drugs that may cause endocrine disorders should be banned, and high-fat and fried foods should be avoided, and a light diet should be maintained.