Disorders of the Nails

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Chapter 655 Disorders of the Nails

Nail abnormalities in children may be manifestations of generalized skin disease, skin disease localized to the periungual region, systemic disease, drugs, trauma, or localized bacterial and fungal infections (Table 655-1). Nail anomalies are also common in certain congenital disorders (Table 655-2).

Table 655-1 WHITE NAIL OR NAIL BED CHANGES

DISEASE CLINICAL APPEARANCE
Anemia Diffuse white
Arsenic Mees lines: transverse white lines
Cirrhosis Terry nails: most of nail, zone of pink at distal end (see Fig. 655-3)
Congenital leukonychia (autosomal dominant; variety of patterns) Syndrome of leukonychia, knuckle pads, deafness; isolated finding; partial white
Darier disease Longitudinal white streaks
Half-and-half nail Proximal white, distal pink azotemia
High fevers (some diseases) Transverse white lines
Hypoalbuminemia Muehrcke lines: stationary paired transverse bands
Hypocalcemia Variable white
Malnutrition Diffuse white
Pellagra Diffuse milky white
Punctate leukonychia Common white spots
Tinea and yeast Variable patterns
Thallium toxicity (rat poison) Variable white
Trauma Repeated manicure: transverse striations
Zinc deficiency Diffuse white

From Habif TP, editor: Clinical dermatology, ed 4, Philadelphia, 2004, Mosby, p 887.

Table 655-2 CONGENITAL DISEASES WITH NAIL DEFECTS

Large nails Pachyonychia congenita, Rubinstein-Taybi syndrome, hemihypertrophy
Smallness or absence of nails Ectodermal dysplasias, nail-patella, dyskeratosis congenita, focal dermal hypoplasia, cartilage-hair hypoplasia, Ellis–van Creveld, Larsen, epidermolysis bullosa, incontinentia pigmenti, Rothmund-Thomson, Turner, popliteal web, trisomy 13, trisomy 18, Apert, Gorlin-Pindborg, long arm 21 deletion, otopalatodigital, fetal alcohol, fetal hydantoin, elfin facies, anonychia, acrodermatitis enteropathica
Other Congenital malalignment of the great toenails, familial dystrophic shedding of the nails

Abnormalities in Nail Shape or Size

Anonychia is absence of the nail plate, usually a result of a congenital disorder or trauma. It may be an isolated finding or may be associated with malformations of the digits. Koilonychia is flattening and concavity of the nail plate with loss of normal contour, producing a spoon-shaped nail (Fig. 655-1). Koilonychia occurs as an autosomal dominant trait or in association with iron deficiency anemia, Plummer-Vinson syndrome, or hemochromatosis. The nail plate is relatively thin for the first year or two of life and, consequently, may be spoon-shaped in otherwise normal children.

image

Figure 655-1 Spoon nails (koilonychia). Most cases are a variant of normal.

(From Habif TP, editor: Clinical dermatology, ed 4, Philadelphia, 2004, Mosby, p 885.)

Congenital nail dysplasia, an autosomal dominant disorder, manifests at birth as longitudinal streaks and thinning of the nail plate. There is platyonychia and koilonychia, which may overgrow the lateral folds and involve all nails of the toes and fingers.

Nail-patella syndrome is an autosomal dominant disorder in which the nails are 30-50% of their normal size and often have triangular or pyramidal lunulae. The thumbnails are always involved, although in some cases only the ulnar half of the nail may be affected or may be missing. The nails from the index finger to the little finger are progressively less damaged. The patella is also smaller than usual, and this anomaly may lead to knee instability. Bony spines arising from the posterior aspect of the iliac bones, overextension of joints, skin laxity, and renal anomalies may also be present. Nail-patella syndrome is caused by mutations in the transcription factor LMX1B gene.

For a discussion of pachyonychia congenita, see Chapter 650.

Habit tic deformity consists of a depression down the center of the nail with numerous horizontal ridges extending across the nail from it. One or both thumbs are usually involved as a result of chronic rubbing and picking at the nail with an adjacent finger.

Clubbing of the nails (hippocratic nails) is characterized by swelling of each distal digit, an increase in the angle between the nail plate and the proximal nail fold (Lovibond angle) to >180 degrees, and a spongy feeling when one pushes down and away from the interphalangeal joint, because of an increase in fibrovascular tissue between the matrix and the phalanx (Fig. 655-2). The pathogenesis is not known. Nail clubbing is seen in association with diseases of numerous organ systems, including pulmonary, cardiovascular (cyanotic heart disease), gastrointestinal (celiac disease, inflammatory bowel disease), and hepatic (chronic hepatitis) systems, as well as in healthy individuals as an idiopathic or familial finding.