The edge of the male nipple a long time there is a circle of dots may be sebaceous gland hyperplasia, contact dermatitis, eczema and other diseases. 1. Sebaceous gland hyperplasia: Sebaceous gland hyperplasia is due to the enlargement of sebaceous glands within the normal skin, or may be caused by inflammatory stimulation, low immunity, hormone level abnormality induced. Patients may appear in the chest rice-like papules, yellowish or yellowish-white, manifested as a circle of dots on the edge of the male nipple for a long time. 2. Contact dermatitis: contact dermatitis may be caused by exogenous substances such as animals, plants, clothing, soap, antiperspirant and other stimulation of the skin. Patients may appear pinpoint-sized dense pimples, and accompanied by erythema, edema, itching and other symptoms, may be manifested as a circle of dots on the edge of the male nipple for a long time. 3. Eczema: Eczema may be genetic, immune abnormalities, endocrine disorders and other factors. Patients may appear corn-like papules, papules, blisters, etc., some patients may suffer from a circle of dots on the edge of the nipple for a long time. In addition, traumatic factors may also appear similar clinical manifestations, leading to a circle of dots on the edge of the male nipple for a long time for a number of reasons, it is recommended that the patient to go to the regular hospital, timely identification of the cause of the disease.