Dermatology is an aspect of medicine dealing with the skin. It is a specialty with both medical and surgical aspects. A dermatologist is a specialist medical doctor that manages diseases related to skin, hair, nails, and some cosmetic problems. Many are trained in their residency on the use of botulinum toxin, fillers, and laser surgery. Some dermatologists perform cosmetic procedures including liposuction, blepharoplasty, and facelifts. Most dermatologists limit their cosmetic practice to minimally invasive procedures. Despite an absence of formal guidelines from the Board of Dermatology, many cosmetic fellowships are offered in both surgery and laser medicine.