Hello Doctor Every year without fail especially during the summer time i get big round blisters on my feet and calf area. Some of them when left alone have grown to about 2cm in diameter. However its when i pop them that the problem begins. for example i have one really big on about 2 cm in diameter and i poped it after a week and at first it was healing normally however after about a week i started to notice that the skin around the wound became black and hard. Its been almost 2 years and that are is still the same size,same blackness and just as hard. with some of the older ones I ve had it takes an average of 5 years for the wound to become a scar . Could you please tell me what i can do to stop this and my legs are completely scared from all these black craters.