Black heel a minor hazard of sport.

Wilkinson DS. Cutis 1977 Sep;20(3):393-6.

“Black heel” (calcaneal petechiae) is a traumatic lesion affecting the back or posterolateral aspect of the heel. It is seen almost exclusively in adolescentes or young adults engaged in active sports, notably basketball, but also football, lacrosse, tennis, and so forth. The lesion is disposed horizontally at the upper dege of the calcaneal fat-pad and consists of grouped punctate hemorrhages, the nature of which is revealed by repeated paring of the lesion. The nature of the pigment is shown by specialized stains. “Black heel” is probably more common than is realized. It is likely to be cuased by a shearing or pinching stress from abrupt contact of th foot with a floor or hard ground. As it si usually symptomless, it may be disregarded or only observed by chance. However, it has been confused clinically with a melaonoa, and as it is such a trivial self-healing process, it is important that it be recognized for what it is.