[The use of nails to diagnosis diseases].

For those interested in nails, a fairly good knowledge of the anatomy of the nail unit is indispensable. But nothing will replace a careful, clinical examination of the nail apparatus. The shape of the nail, surface abnormalities and coloration, with or without a magnifying glass, may well provide a medical diagnosis not only in dermatology but also for medicine in general. Pits on the surface of the nail plate may be enough to diagnose psoriasis on a limited area of scalp dandruff. Even partial detachment of the nail apparatus might lead to the suspicion of psoriatic arthritis. A triangular lunula is associated with the absence of patellas. Finally, no pulmonary examination of a smoker is complete without looking for clubbing. It is high time to pay tribute to the nail.