Tinea cruris is the name used for infection of the groin with a dermatophyte fungus. It is most often seen in adult men. Tinea cruris is commonly known as jock itch.
In different parts of the world, different species cause tinea cruris. In New Zealand, Trichophyton rubrum and Epidermophyton floccosum are the most common causes. Infection often comes from the feet (tinea pedis) or nails (tinea unguium) originally, spread by scratching or the use of an infected towel.
The appearance is similar to ringworm (tinea corporis). The rash has a scaly raised red border that spreads down the inner thighs from the groin or scrotum. Tinea cruris may form ring-like patterns on the buttocks. It is not often seen on the penis or vulva or around the anus. Tinea cruris can be very itchy.