A movable bag growing on the foreskin of the penis is mostly considered to be sebaceous cysts or lipomas, etc. If accompanied by other discomforts, it is recommended to go to the hospital for further examination.
Due to the extensive distribution of sebaceous glands on the surface of the foreskin of the penis, therefore, in general, if there is a long bag on the foreskin of the penis, and the degree of mobility is high, then it can be considered to be due to the usual lack of attention to personal hygiene, not timely cleaning led to the emergence of sebaceous cysts, and we can consider the medication of anti-infective treatment or surgical resection, etc..
In addition, it can not be ruled out that there is a small lipoma or varicose blood vessels that lead to the appearance of a movable lump on the foreskin of the penis.
Therefore, if accompanied by other discomforts, it is recommended to go to the hospital for further examination to clarify the diagnosis.