Most of the white solids in the nipple crease belong to sebaceous gland secretion, or may be inflammatory substances or nipple overflow. 1. Sebaceous gland secretion: There are many folds on the surface of the nipple, so the sebaceous secretion on the surface of the nipple can easily accumulate, thus causing the phenomenon of white solid in the nipple crevice. 2. Inflammatory substances: If there is mastitis, there may be inflammatory substances in the nipple, which will lead to the phenomenon of white solids in the nipple crevice, accompanied by breast swelling and pain. 3. Nipple discharge: If a woman is breastfeeding, her nipples will produce a lot of milk, so nipple discharge can also lead to the phenomenon of white solid nipple crevice. At the same time, breast duct dilatation, breast hyperplasia, breast cancer and other diseases may appear nipple discharge, will also appear nipple gap with white solid, need to be identified accordingly. There are many reasons for white solid nipple gap, it is recommended to go to the hospital in time to improve the examination, clear diagnosis, do not ignore the symptoms, take it lightly, so as not to delay the treatment of the condition.