Information from the AOCD:

As complete physicians of medicine, D.O.s specialize in all the major specialties and subspecialties. D.O.s who specialize in dermatology have completed a rigorous program of medical education and training that includes:

• Obtaining an undergraduate B.S. or B.A. degree.
  
• Completing four years of general medical education at one of 20 federally accredited osteopathic medical schools resulting in the awarding of the D.O. (Doctor of Osteopathy) degree.
  
• Completing a one year federally accredited internship program in general medicine.
  
• Completing a three year federally accredited residency program in dermatology.
  
• Dermatology subspecialists have one to two more years of subspecialty training.
  
  

The training for an osteopathic dermatologist is the same as an allopathic or M.D. dermatologist. The curriculum consists of concentrated study of skin, hair and nails. Although physicians in other specialties, based on their training and level of personal interest may feel comfortable with basic skin problems, the physician emerging from this training, whether D.O. or M.D., will have the greatest degree of knowledge and understanding of how to approach and care for the largest organ of the body - the skin. Dermatologists focus on how your skin, hair and nails affect (and is affected by) your health.