Section 29: Disorders of Nails and Hair

Clubbed nails 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.

Trachyonychia 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. The nails have a rough, sandpaper-like quality as well as longitudinal ridging and occasional splitting at the distal nail edge. When all nails are involved, the condition that has been termed twenty nail dystrophy of childhood. Similar nail changes can be seen in lichen planus and alopecia areata. In many patients the condition spontaneously regresses.

Traumatic onychodystrophy (Habit tic deformity) Trauma to the nail plate or nail folds can produce a wide variety of nail deformities. The one pictured in Fig. 29-3 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.

Dystrophia unguis mediana canaliformis 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.

Leukonychia totalis This is a rare nail disorder that is inherited in autosomal dominant fashion. The color of normal nail plates beyond the lunulae is normally pink from the blood in the blood vessels of the nail bed. The whiteness shown in Fig. 29-5 is due to an abnormality in the nail plate. The nails may also be brittle.

Leukonychia striata The horizontal white streaks pictured in Fig. 29-6 are the result of abnormal keratinization of the nail plate. The tendency toward leukonychia striata is sometimes inherited in an autosomal dominant ...