Treating Dark Spots on Legs from Mosquito Bits

I've had dark spots on my legs for almost more than 2 to 3 years now which was caused by mosquito bites. I would like to have them removed and my dermatologist schedule me to do microdermabrasion at the end of this week and also he put me on retin A, hydroquinone for a week or so. I just want to find out if one treatment is enough to remove the marks as my dermatologist told me and would other treatment like TCA peel work better? i want to see immediate result if possible