Jock itch is a fungal infection of the groin and upper thighs.
Lesions caused by jock itch can extend from the crease between the inner thigh and pelvis, over the adjacent upper inner thigh, and into the anal area. Jock itch occurs when the groin area becomes sweaty, allowing fungi to build up. It can also crop up through a transfer of athlete's foot, or from contact with clothing, bedding and towels of infected individuals.