Tinea cruris is caused by fungi, so like other tinea diseases, there must be an environment suitable for the growth and reproduction of fungi, as well as the source of fungi, that is, the source of infection. Tinea cruris is a tinea disease that occurs in groin, upper part of inner thigh and vulva.

The most common part is the thigh skin on the opposite side of scrotum. At first, the damage is a small maculopapular rash with red color and small scales on the surface. Subsequently, the rash expanded and gradually spread around, forming annular or semi-annular patches. Generally, it is aggravated in summer, and the skin lesions in winter are obviously reduced. Generally speaking, tinea cruris mostly occurs in men, because the inner thigh of men is close to scrotum, especially the obese people are completely stuck together, and the secretions and dirt on it are not easy to remove, and the local temperature is high and humid, which is very suitable for the growth and reproduction of fungi, so men are prone to tinea cruris. In addition, the occurrence of tinea cruris is also related to the decrease of the body's resistance