Men with white rice grains in the coronal groove may be caused by circumcision, glans phimosis, penile pearly papules, warts and other causes. 1. Circumcision: men have a long foreskin, not often wash the inside of the foreskin, may generate a large amount of circumcision scale, it will make the coronal groove area there is a white rice-like material. 2. Foreskin glans inflammation: it may be related to the lack of attention to physical hygiene, which may lead to fungal or bacterial infection inside the foreskin, which will make the coronal groove white grains, accompanied by itching, tingling and other symptoms. 3. Penile pearly papules: a benign lesion, manifested as white rice-sized pimples in the coronary groove area, usually without any uncomfortable symptoms, and will not affect the health of the reproductive system, usually do not need special treatment. 4. Warts: mainly caused by human papillomavirus infection, usually associated with unclean sex, may also be caused by indirect contact, can lead to the coronary groove area of the white rice size pimples. There are a lot of reasons why men have white grains on their crowns, and it is recommended that they go to the doctor for the appropriate examination and treatment.