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MISCELLANEOUS

Trachyonychia

Various diseases can disrupt the nail matrix, causing the surface of the plate to be rough and lacking in luster. Any number of finger- and toenails may become rough or ridged (Figs 29.49 and 29.50). When all the nails are affected, the term twenty-nail dystrophy has been used. Trachyonychia is usually idiopathic but may be caused by alopecia areata, psoriasis, lichen planus, or rarely pemphigus vulgaris. A fungal cause of nail dystrophy should always be considered, especially if only the toenails are involved. Biopsy of the nail matrix may be done to establish a diagnosis, although this is usually not indicated, as permanent nail deformity may result. Young males from 10 to 20 years are most commonly affected.

    Any associated skin disease should be looked for and, if found, treated. If lichen planus is the cause, low-dose systemic steroids (e.g. 20mg/day) have been used with success. Most of the time, no cause will be found and no treatment indicated or available. Spontaneous resolution commonly occurs.

Figure 29.49 Trachyonychia. The nails are rough, lacking luster, and have been sandpapered.

Figure 29.50 Trachyonychia. More prominent nail plate damage compared with Figure 29.49.

Splinter hemorrhages

A longitudinal linear red or black streak below the nail is characteristic. Common ‘benign' splinter hemorrhages occur in the middle or distal nail bed and are usually black at the time they are noticed (although all splinter hemorrhages are initially red; Fig. 29.51). They were seen in approximately 16% of elderly patients in one study. This contrasts with the rarer splinter hemorrhages associated with systemic disease (e.g. subacute bacterial endocarditis), which initially occur more proximally and often include red lesions, presumably because new crops are constantly occurring.

Figure 29.51 Splinter hemorrhages. The ‘benign’ type.

Pachyonychia congenita

See Figure 29.52 and Chapter 15.

Figure 29.52 Pachyonychia congenita.

Koilonychia

The nail is concave with the plate thinned and the edges everted in koilonychia, also known as spoon nails (Fig.29.53). It occurs not uncommonly in children on the hallux and may be familial. Associations include occupational trauma, thumb sucking, iron deficiency anemia (Plummer–Vinson syndrome), and many others. Systemic causes generally affect all nails by comparison with traumatic causes. Any underlying abnormality should be corrected.

Figure 29.53 Koilonychia. Note the spoon-shaped curve of the nail.

Parrot beak nails

Longitudinal hypercurvature of the nails occurs in parrot beak nails (Fig. 29.54).

Figure 29.54 Parrot beak nails.

Median canalicular dystrophy

A midline longitudinal split of the nail (usually the thumbnail) occurs in median canalicular dystrophy (Fig.29.55). Lines extending outward on both sides give the appearance of a fir tree (Fig.29.56). No treatment is needed or known to be effective. Spontaneous remission may occur.

Figure 29.55 Median canalicular dystrophy. The cause of this ridge running down the middle of the nail is unknown.

Figure 29.56 Median canalicular dystrophy of both thumbs, showing a fir tree pattern.

Brachyonychia (racket nails)

The thumbnail is wider than long, resulting from a congenitally short distal phalanx (Fig.29.57). It may be bilateral and sometimes shows autosomal dominant inheritance. Rarely, brachyonychia is acquired in relation to hyperparathyroidism. Genetic counseling should be offered in the congenital type.

Figure 29.57 Brachyonychia of thumbnail, congenital type.

Malalignment of the toe

The great toe may be congenitally malaligned or may acquire this abnormality (Fig.29.58). The nail plate is thick and curves laterally, with ridging of the nail plate. The plate itself is hard, distinguishing it from the more fragile nature of the plate in onychomycosis. If mild, trimming may be all that is needed. If severe, surgical realignment can be done. Specifically, surgical excision of the dorsal expansion of the lateral ligament permits immediate correction of the anomaly without nail plasty.

Figure 29.58 Malalignment. Note that the nail is growing diagonally out from the root. The nail often thickens significantly as well. This change may be congenital or acquired.

Ridges

Nail ridges are common in the older patient (Fig.29.59). No effective treatment exists.

Figure 29.59 Ridges of the nails are common in older patients. The ridges may have a longitudinal beaded appearance, resembling a row of sausages.

Brittle nails (onychorrhexis)

Roughness and irregularity of the distal nail plate in an elderly patient is characteristic of this condition (Fig.29.60). Women are more commonly affected than men, and wet working conditions may aggravate the symptoms. Those factors that dry out the nail, including excessive wetting and drying, should be avoided. Soaking the nails for 10min a day, often best done at night, and applying petrolatum afterward may be tried. Some recommend application of nail enamel once a week if this fails. Biotin (e.g. 2500 mg/day) has been reported to be effective in several retrospective or uncontrolled studies.

Figure 29.60 Brittle nails. As the patient ages, the hair, skin, and nails thin. The distal nail plate becomes brittle and breaks easily.

Lamellar dystrophy (onychoschizia)

There is a separating layer at the distal end (Fig.29.61). This change is common in older individuals, or in association with brittle nails. There is no reliable way to prevent future occurrences.

Figure 29.61 Onychoschizia, also known as lamellar dystrophy, is probably due to repeated wetting and drying of the nails.

Nail hypertrophy and onychogryposis

Opaque, thickened nails, with exaggerated growth upward or laterally, are characteristic of nail hypertrophy (Fig.29.62). Old age and trauma are the primary causes. If the nails are permitted to grow, they may take on the appearance of a horn (Fig. 29.63). This is called onychogryposis.

    With the appropriate tools, one can mechanically drill and burr for initial therapy, followed by routine trimming. Podiatrists often perform these treatments. Definitive therapy involves nail avulsion and matrix ablation.

Figure 29.62 Nail hypertrophy in an older patient. Note how the thickened nail has curved back to the toe and is actually digging into the skin.

Figure 29.63 Massive onychogryposis reminiscent of goat hoofs that have not been cut in years. (Courtesy of Dr. S. Natarajan.)

Pincer nails

Deformity of the nail (usually a toenail, but multiple nails may be affected) occurs by inward folding of the lateral edges (Figs 29.64–29.66). The nail bed is drawn up between the edges and pain may be significant. Most cases are not painful enough to warrant intervention. For mild cases, cutting out the sides of the nail monthly may be sufficient. In severe cases, partial avulsion of the lateral sides may provide relief. Ultimately, complete nail ablation can be done.

Figure 29.64 Pincer nails. The nail curves inward and pinches the nail bed and the tissue immediately below.

Figure 29.65 Pincer nails. The curvature of the nail is complete.

Figure 29.66 Pincer nails. Bilateral lesions.

Practice point

fi Always consider congenital abnormalities in the differential diagnosis of nail dystrophy in children, especially if changes in nail size or thickness are symmetric and are not associated with tinea pedis.

Ingrown nail

Etiology and pathogenesis

Normally, the nail plate grows out smoothly and does not irritate the lateral nail fold. However, if any process inflames the lateral nail fold, such as trauma or infection, the swollen tissue may be driven into the nail plate. A vicious cycle results as the nail burrows deeper into the skin, causing a foreign body response, producing more swelling, etc. Factors that contribute to the problem include ill-fitting shoes that compress the toe laterally.

Clinical

A swollen, red, lateral nail fold, which extends over the lateral edge of
the nail, is characteristic (Fig.29.67). It usually affects the hallux in an adolescent or young adult.

Figure 29.67 Ingrown nail. Note the tremendous tissue inflammation and the nail driving its plate through the center.

Differential diagnosis

It is usually a simple diagnosis, but some causes of inflamed periungual skin (Table 29.2) may need to be considered.

Treatment

An oral antibiotic, warm soaks, cutting the nail straight across, and using tape to pull the tissue away from the nail may be tried initially. Placing a wisp of cotton between the lateral nail plate and the soft tissue, thus slowly raising the plate up and out of the swollen tissue, has been advocated. If these measures fail or if rapid relief is needed, removal of the lateral third to half of the nail can be done (Fig.29.68). If recurrences are a problem, ablation of the nail matrix on that side may be done. The patient should be warned of the cosmetic deformity.

Ablating the nail may be done as follows. Begin oral antibiotics for 10 days prior to the surgery. Clean the nail and perform a digital block or slow local infiltration of anesthetic. When anesthetized, apply a tourniquet (e.g. thumb of a glove with a hole cut in the tip and the base twisted with a clamp), then avulse one-third of the nail on the affected side with special nail clippers. Apply phenolic acid on a Q-tip to the matrix for 30s, three times (90s in total). Try to avoid contact with normal skin. Then wrap. Have the patient soak the area, followed by an antibiotic or bland ointment and dressing twice daily.

Figure 29.68 Partial nail avulsion. Surgical removal of the plate removes the foreign body irritation that creates all the inflammation. The thumb area of a glove is used as a tourniquet.

White/Cox: Diseases of the Skin, 2ed.(c) 2006, Elsevier Inc. All rights reserved.