Increased curvature of the nail plate may be due to a wide variety of causes. In this patient, the large, convex nails are a hereditary anomaly and were found to be present in both father and brother. Other causes of clubbing of the nails in children include cyanotic congenital heart disease, cystic fibrosis, and chronic inflammatory bowel disease.
Any skin disease that affects the nail matrix may result in an abnormal nail plate. There are children, though, who only manifest dystrophy of the nail without any other cutaneous lesions, a condition that has been termed twenty nail dystrophy of childhood. The nails have a rough, sandpaper-like quality as well as longitudinal ridging and occasional splitting at the distal nail edge. Similar nail changes can be seen in lichen planus and alopecia areata. In many patients the condition spontaneously regresses.
Trauma to the nail plate or nail folds can produce a wide variety of nail deformities. The one pictured here is the result of a habit tic. This common nail dystrophy is characterized by a longitudinal canal that runs down the center of the entire nail plate. It is caused by manipulation of the proximal nail fold by the index finger of the same hand.
This is a rare condition of unknown etiology that usually involves the thumb. It consists of a canal that runs near the center of the length of the nail plate. Small cracks that extend laterally from the linear canal give the appearance of an inverted fir tree. This deformity tends to resolve spontaneously over a period of months but often recurs.
This is a rare nail disorder that is inherited in autosomal dominant fashion. The color of normal nail plates beyond the lunulae is largely pink from the blood in the blood vessels of the nail bed. The whiteness shown here is due to an abnormality in the nail plate. The nails may also be brittle.
The horizontal white streaks pictured here are the result of abnormal keratinization of the nail plate. The tendency toward leukonychia striata is sometimes inherited in an autosomal dominant fashion. In other cases, it can be attributed to vigorous manicuring, to trauma, or to a wide variety of systemic illnesses. In many patients, there is no obvious cause, and the streaks resolve spontaneously.