A dermatologist studies and treats diseases of the skin, hair and nails. Some dermatologists specialize in nail pathology, which is the science of the causes and effects of nail diseases.
A dermatologist who specializes in the treatment of nail disorders can perform biopsies and excisions on the nail to determine the cause of infection, inflammatory disease, cosmetic issues or cancer. Diseases of the nail that are commonly diagnosed include onychomycosis, or fungus, and paronychia and pseudomonas, which are both forms of bacterial infection. In nails that show possible signs of cancer, a biopsy is typically performed, and the nail is removed for further testing.