I have several small, dry, itchy, slow healing sores on my lower legs. It feels good to scratch them, like poison oak sores do. It also feels good to spray very hot water on them, also like poison oak sores do. There is no pus, only some light scabbing that bleeds profusely when scratched off. Moisturizing lotion seems to make the itching worse. In the shower I always clean with soap. All other cuts, bruises, etc. on my body heal just fine and quickly. I realize that scratching impedes the healing process, but I try not to scratch, and feel they should have healed by now regardless. One of the sores, the first, is about 2" in diameter, and I've had it for 6 months or more. And as a side note, dogs are very interested in this one sore in particular. I always wear shorts, and every dog I encounter has to sniff and sniff that sore.
I forgot to add that dogs like blood so that's probably why they're sniffing your sores.
I have had an itchy sore on the back of my leg just below the knee for a LONG time. It sounds exactly like the ones you describe. I have no idea what it is but a clue might be that I had a terrible (really terrible) case of poison ivy a few summers ago that took months and months to heal and left residual spots for more than a year.
I looked it up just now for the same reason you apparently did (is it the big "C"?). But now I'm back to wondering if it's just my body continuing to defend itself by producing (too much) histamine....basically an allergy to something that's no longer there....hope this helps.