Knuckle pads from boxing.

A 21-year-old man developed painful hyperkeratotic, fissured, callosities on his knuckles ("knuckle pads") after having boxed for five evenings a week for six months. Boxer's knuckle pads are one type of traumatic skin injury regularly found in athletes, such as "jogger's toe", "athelete's nodule", "jog-ger's nipple", "runner's rump", "runner's bump", "rower's rump", "tennis toe", "skier 's shin", "surfer's nodule" "black heel", "black palm", "jazz ballet bottom" and "stria distensae". These types of traumatic skin injuries are briefly reviewed here.