Sebaceous ectasia refers to the sebaceous glands that grow on the foreskin, which may be due to physiologic and pathologic reasons, including endocrine disorders, skin trauma and other reasons. 1. Physiological reasons: it may be due to the excessive secretion of oil in the prepuce skin which leads to denaturation, and thus the appearance of prepuce sebaceous gland ectasia. It can also be accompanied by hair loss, acne and other symptoms. 2. Pathologic causes: (1) Endocrine disorders: this phenomenon may occur due to endocrine disorders caused by various reasons, which may result in degeneration or hyperplasia of the foreskin caused by exuberant secretion of sebaceous glands. (2) Skin trauma: when the foreskin skin tissue is damaged, it is easy to be infected by microorganisms and form scar, which will lead to this phenomenon. In addition, the foreskin sebaceous ectasia can be seen in other conditions, and patients are advised to go to the hospital in time.