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NAIL CHANGES SECONDARY TO TRAUMA

Punctate leukonychia

When formation of the nail is disturbed, a white area results. Although commonly, and erroneously, blamed on calcium deficiency, this is actually due to incidental minor and unnoticed trauma, causing a partial, acquired leukonychia in which small white dots are seen within the nail.

    Other types of leukonychia are discussed in the section on nail pigmentation (see Figures 29.46–29.48).

Subungual hematoma

A red, blue, or purple lesion occurring after trauma is characteristic (Fig.29.18). A variety of sporting activities (e.g. surfing) may precipitate a lesion. No treatment is needed. If very large, painful, and acute, a small hole may be made in the nail plate to allow drainage.

    The main problem is that, especially when affecting the hallux nail, the preceding trauma may pass unnoticed (by contrast to with fingernails, where any trauma sufficient to cause a subungual hematoma usually provokes an immediate expletive).

    Some points that help to distinguish hematoma from melanoma are listed in the Practice points box. One of particular importance is that melanoma usually involves the skin of the distal digit or of the lateral or proximal nail folds ( Hutchinson sign). However, the clinician also needs to be aware of pseudo-Hutchinson sign, in which the color of a hematoma is visible through the thin skin of the proximal nail fold (Fig. 29.18c).

Figure 29.18 Subungual hematoma. (a–c) These pigmentary changes are clearly caused by blood. A melanoma would emanate from the matrix in a longitudinal fashion, with straight lateral edges.

PRACTICE POINTS

Habit tic deformity

The habit tic deformity is caused by repeated picking of the middle of the proximal nail fold, which causes repeated damage to the nail matrix. The picking is usually done with a finger on the same hand. The thumbnail is usually affected, but the potential is there for all nails. A depression of the cuticle where the picking occurs is usually seen. Usually, the underlying factors of this condition are similar to those of an obsessive compulsive disorder. A series of transverse lines make the thumbnail look like a washboard in the habit tic deformity (Fig. 29.19).

    The object of any treatment is to get the patient to stop picking. Sometimes, merely making the patient aware of the cause is enough, although some will deny absolutely that they pick at the nail. Often, however, the patient needs ‘help' to stop this habit. Serotonin reuptake inhibitors such as fluoxetine, fluvoxamine, or sertraline have been used successfully with obsessive compulsive disorder, and have also been used with success in anecdotal reports for this ‘habit tic'. One should use caution, however, as sexual dysfunction is a common side effect.

Figure 29.19 Habit tic deformity. Note the similarity to a washboard. Chronic picking at the proximal nail fold where the alteration begins is the cause.

Skier's toe, footballer's toe

A subungual hematoma may form from chronic repetitive trauma to the nail, typically minor shearing damage as occurs when a skier's toe repeatedly presses against the ski boot (Fig.29.20) or when a football is kicked. It is often bilateral and usually affects only each hallux. No treatment is needed.

Figure 29.20 Skier’s toe.

Onychophagia

Onychophagia, or nail biting, is a habit, most common in children, that results in a shortened, split, and irregular distal nail plate (Fig.29.21). The patient should be encouraged not to bite. A distasteful topical substance may be applied to the nail. A double-blind study showing some benefit with clomipramine or desipramine has been reported. Sucking a digit is common in young children and may lead to onycholysis or to chronic paronychia, which may be inappropriately treated as fungal infection (Fig.29.22). This habit may occur at night, so parents may deny that it happens. There may be associated eczema on the cheek due to the irritant effects of saliva (Fig.6.39).

Figure 29.21 Onychophagia. All the distal tips are gnawed short, and the skin is roughened.

Figure 29.22 Thumb sucking. Chronic thumb sucking in a young child has caused a soft nail with koilonychia and onycholysis. Resolution is usual, but it can be dif?cult to persuade parents that this is the cause, even if the child sucks the digit throughout the clinic visit.

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