Hidradenitis suppurativa is a common congenital developmental abnormality that occurs in children. The common presentation is that the body of the penis is retracted inside the body, and only the small pointed foreskin is exposed. When the skin of the penis is squeezed inward by hand, the body of the penis is revealed, and when the hand is released, it is retracted back into the body. Hidden penis needs to be distinguished from micropenis, hypospadias, and phimosis. The first two are caused by endocrine defects or chromosomal abnormalities, which can be seen clinically as small penile body, less erection and weak erection; the latter is caused by the narrow opening of the foreskin, so that the head of the penis can not be exposed. If you have a congenital disease such as cryptogenic penis, it is best to treat it as soon as possible, because if it is allowed to develop and remain hidden in the body for a long time, it will cause the penis to be unable to extend outwardly, and the growth and development of the body of the penis will be seriously affected, i.e., the growth will be restricted, resulting in a short penis in the future, or even infertility. Parents should take their children with hidden penis to regular hospitals for treatment as soon as possible to avoid delay.