Nails and nail disorders in children and adults.

Abnormalities of the nails can provide both subtle and obvious clues to common medical problems or severe systemic diseases. Heredity, minor injuries and a variety of infections account for many changes in the appearance of nails. Several dermatologic disorders, such as psoriasis and alopecia areata, and other multisystem disorders may present with nail changes; abnormalities of the nails may be the single most prominent feature. Common habits and the use of various cosmetics also may result in nail changes. Awareness of normal nail variants and well-defined abnormalities and their disease associations will be beneficial to most clinicians. Specific management and therapy for most nail problems are usually simple and appropriate for primary care physicians.