Is it safe to have microdermabrasion if I had keloids/raised scars as a child?

Microdermabrasion is a very safe procedure.  Microdermabrasion removes only the very superficial (surface) layers of the epidermis.  It's like buffing your car.  Dermabrasion however is a much more aggressive skin resurfacing procedure.  Dermabrasion is quite effective in resurfacing the skin in appropriately chosen patients.  It has fallen out of favor in the past years due to its messiness and other efficacious skin resurfacing modalities such as ablative skin resurfacing (e.g. CO2 laser, fraxel and such).  However, microdermabrasion is typically a spa treatment.  It will temporarily brighten your skin.  It is a good treatment to repeat regularly but it will not really transform your skin that substantially unless you are combining it with other skin health treatments.  I recommened GOOD home skin care.  Get a Clarisonic brush and some good skin care products.  We (my staff and I) are currently using the ZO products.  There are other good skin care products on the market but we like Dr. Obagi's new line.  I have no financial ties to Clarisonic or ZO medical.  You should like the microdermabrasion and there should be no significant side effects.  Your skin may be "pink" for a few hours after the treatment. Good luck.  BTW, there are many different types of microdermabrasion.  Some use "crystals" or microparticles to remove the dead skin and other machines are non-crystalline.  Personally I like the non-crystalline units.  Do some research but you should not worry about forming unacceptable scarring.