A pimple the size of a grain of rice on the foreskin of the penis is closely related to local tissue abnormalities, the causes of the corresponding conditions mainly include cornu rashes, warts and inflammation. 1. Corns: are caused by localized follicle blockage and fat deposition, most of which will not be accompanied by obvious clinical symptoms. 2. warts: and HPV virus infection has a correlation, after the virus infection leads to local tissue bulging, there will be related symptoms, some will be accompanied by obvious itching and stinging. 3. Inflammation: local hygiene deviation leads to inflammation, will also cause related symptoms, most of the accompanied by red, swollen and painful performance. Penile foreskin corresponding condition, has not been improved, and obvious pain and discomfort, you need to timely medical observation, diagnosis of the condition, and standardized treatment under the guidance of the clinician, to avoid delays in the condition.