Athlete's nodule.

Three cases of athlete's nodule on the feet are reported. In case 1, a 30-year-old man, who had been an amateur football player, presented with nodules on the lateral side of the feet and on the right lateral malleolus with a duration of 1 year. In case 2, a 22-year-old man, who had participated in karate and track-and-field, presented with nodules on the lateral side of the feet and on the right lateral malleolus with a duration of 10 years. In case 3, a 25-year-old man, who had skied, presented with a nodule on the right lateral malleolus with a duration of 4 years. The biopsy specimens from the lesion demonstrated hyperkeratosis, acanthosis of the epidermis and thickness of the dermis. In 1991, Cohen et al. proposed the concept of athlete's nodule which indicated an acquired cutaneous nodule caused by chronic stimuli with sports. Histopathology of the athlete's nodule shows hypertrophy of the epidermis and dermis. To the best of our knowledge the term "athlete's nodule" has not been used in Japan, but it is a useful term to refer to the lesion induced by athletics or the use of sporting equipment.