A pinch callous forms when there is friction against skin – usually the side of the big toe or or under the little toes. This is a patient’s healed pinch callous that formed during a marathon which I mostly shaved off.
This is the shoe which was used during the marathon. Notice the distinct red color, corresponding to the pinch callous bleeding into this runner’s sock and shoe? In this case the problem was the trim on the shoe, gouging into the pinch callous with each running step.
The cure?…a little surgery to excise the offending trim and voila! No more pressure, no more bleeding. The hole was made by this person’s foot, but cutting into the mesh would be fine too.