Nails

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chapter 35 Nails

INTRODUCTION AND OVERVIEW

Nails are important for adornment. Smooth, lustrous nails are considered a sign of health and beauty. The rapid growth of nail salons demonstrates the value that women in particular assign to their nails. Fingernails are also important for fine touch and manipulation. Toenails are protective, especially the large toenails, which bear the brunt of force from jogging, footballing and many other sports.

The nail sits right on the bone of the terminal phalanx, and is closely associated with the distal interphalangeal joint. Toenails especially are prone to repeated microtrauma over the years from footwear, sporting injuries and changes due to arthritis. Fingernails suffer from whatever traumas we put our hands through—chemicals, soaps and detergents and, for some, the added insults of nail salons cutting and dissolving cuticles, using harsh chemicals to apply and remove polishes, false nails, acrylics and so on.

NORMAL NAIL STRUCTURE

The normal nail structure consists of the nail matrix, the nail bed, the proximal and lateral nail folds, the cuticle and the nail plate (Fig 35.1). The nail matrix is made up of the germinative epithelium, and is protected from the environment by the waterproof seal created by the cuticle.

image

FIGURE 35.1 Diagrammatic drawing of an adult fingertip, showing nail structures through a longitudinal midline plane.

The integrity of the nail depends on the close adhesion of the nail bed and the nail plate, as well as an intact cuticle. The nail bed is closely apposed to the distal phalanx, so changes in the bone and joint will affect the nail.

COMMON NAIL PROBLEMS

HYPERTROPHY AND SUBUNGUAL HYPERKERATOSIS

A number of conditions can cause this problem. Fungal infection, psoriasis and trauma are the most common causes, and may coexist. Fungal infection and trauma are most often seen in toenails; it is rare to have fungal disease in fingernails unless all the toenails are involved too.

Onychomycosis (fungal infection)

Onychomycosis is a relatively common nail disease. A recent European study (Achilles) of 90,000 people aged over 60 years in 16 countries estimated that half had a ‘fungal foot infection’ and that one-quarter of these had onychomycosis.1,2 An Australian study of the general population stated the prevalence as 2–8%, but this figure increases with age.3 An Australian nursing home study put the rate at 22%.4

Causes

Most cases of onychomycosis are due to dermatophytes, with Trichophyton rubrum and T. mentagrophytes var. interdigitale being the most common. They usually affect nails by the distal and lateral subungual route. Repeated microtrauma is a common predisposing factor, and tinea between the toes is often present too.

White superficial onychomycosis and proximal subungual onychomycosis may also occur but are less common.

Diagnosis

A diagnosis of onychomycosis should be made before embarking on treatment. Many diseases mimic onychomycosis. Unfortunately, using fungal microscopy and culture, a negative result is obtained in about 40% of cases where infection is truly present. Ideally, when sending a specimen for micro and culture, plenty of the subungual material should be collected and ground up before plating. Distal nail biopsy gives a much higher yield of positive results. Basically this involves cutting off as large a specimen as possible of distal nail (in fact the patient often does this best, and you must stop the nail clipping being lost over on the other side of the room). The piece is sent for histopathology as well as micro and culture, and the pathologist looks for hyphae in the nail plate.

Treatment

One option is to have no treatment apart from regular nail clipping. Oral therapy is usually necessary to cure infections in the nail plate. Other treatment options are:

1. Terbinafine (Lamisil®)—at present the treatment of choice for onychomycosis due to dermatophytes.

The usual dose is 250 mg daily. It comes as 42 tablets and one repeat. In nail clinics patients are often asked to take the second 42 tablets twice a week; this prolongs the therapy and still gives a reasonable dose in the nail plate.

It is important to stress to patients that the infected toenails will need to grow out, and this can take up to a year.

Side effects are normally minimal, but there are some worrying reports of agranulocytosis occurring after a month of therapy. Liver function abnormalities have been reported too. A white cell count and liver function test after a month of treatment are recommended.

2. Itraconazole (Sporanox®)—also highly effective, often given as ‘pulse therapy’. Two tablets twice daily (400 mg) are given for the first week of the month, each month, for 3 months of therapy.
3. Fluconazole—weekly oral fluconazole 150 mg for 3 months is used extensively in many countries.
4. Griseofulvin—500 mg, two tablets per day is usually required to achieve sufficient dosage in the nail. As this drug is only fungistatic, prolonged treatment of up to 2 years may be needed for toenails, especially in the elderly. Even so, the cure rate is around 50% and relapse is common. Nausea and headaches may occur, and liver function tests should be monitored with long-term therapy.
5. Ketoconazole—can be effective but is inadvisable because of potential liver toxicity.
6. Topical therapy—for white superficial onychomycosis or limited disease, topical treatment can be useful, especially in conjunction with removal of diseased nail. Amorolfine (Loceryl®) is the most effective agent currently available in Australia. It is a paint applied weekly after rubbing the nail plate with a file.
7. Physical treatment—nail removal, surgically or with 40% urea paste, can be helpful, especially in single nail disease. It is usually advisable to use topical or oral antifungal treatment as well, or the disease may re-occur.

Psoriasis

Involvement of the fingernails and toenails with psoriasis has been reported in up to 50% of psoriasis sufferers.5 The fingernails are more commonly involved than the toenails.

Pitting and onycholysis are common presentations of nail psoriasis, but the more disfiguring abnormality of hypertrophy and subungual hyperkeratosis is the most distressing. Often all the nails eventually become involved, whereas this is less common in onychomycosis. Fingernails are frequently involved and this appearance upsets patients more than that of their toenails, which can be hidden.

Another difference between onychomycosis and psoriasis is that the nails affected by psoriasis often change; some may recover spontaneously but this does not occur in onychomycosis.

Diagnosis

Distal nail biopsy, as described above, is useful. The pathologist looks for parakeratosis on the nail plate.

Treatment

No treatment is fully effective in all people, and often the patient opts for no treatment.

The following can be used.

1. Topical calcipitriol.
2. Intralesional steroids—Kenacort®-A10 (triamcinolone acetonide), diluted in Xylocaine® (lignocaine), injected into the proximal nail fold and/or nail bed can give several months of remission.
3. PUVA (psoralen plus exposure to ultraviolet A)—topical or oral psoralens with UVA sometimes helps.
4. Oral methotrexate—seldom used for nails alone, but if there is widespread skin involvement or arthritis as well, it can be useful.
5. Oral acitretin—again, seldom used for nails alone, but can be useful for severe hyperkeratosis.

An alternative approach is of a cosmetic nature. Preformed artificial nails or sculptured artificial nails may be applied if there is enough keratin for adherence. Nail abrasion, usually done by podiatrists, can also help with appearance, and in reducing discomfort from footwear.

Trauma

Trauma, especially to the toenails, is one of the most common causes of nail dystrophy. Repeated microtrauma is particularly common, from shoes and sports, especially jogging, netball and football. Changes to underlying bones and joints with arthritis and ageing can exaggerate the effects of trauma.

Onychogryphosis

Onychogryphosis is most common in the big toenails. The nail plate is thickened and opaque and the nail bed is hyperplastic. In the extreme form the nail looks like a ram’s horn. In older patients this is due to biomechanical factors and footwear, and secondary foot anomalies such as hallux valgus are commonly associated.

Pincer nails

Pincer nail deformity is characterised by transverse overcurvature of the nail plate, especially at the distal free edge. The constriction of the distal pulp may be painful, especially in the severe form when the distal phalanx is enclosed. The deformity may lead to ingrown toenails.

The dystrophy is most likely a developmental abnormality for which there may be a hereditary tendency. There seems to be an enlarging of the dorsal bony phalanx with juxtaarticular osteophytes causing widening of the base of the nail, therefore leading to a conical-shaped nail plate.

Treatment with lateral matrix ablation is often necessary, although less invasive treatments have been described.

Habit tic deformity

Habit tic deformity is a deformity usually of the thumb nails, caused by habitual picking and manicuring of the proximal nail fold causing repeated trauma to the nail matrix and resulting in a central depression with transverse grooves at the same angle as the cuticle, giving a washboard or fir tree appearance. Often the cuticle is damaged or absent. This deformity is particularly noticeable in people with large cuticles (Heller’s median canaliform dystrophy).

Nail biting (onychophagia)

Nail biting is common in children—up to 50% of children are affected at some stage. Usually it is self-limiting, but it may persist into adulthood with less likelihood of recovery. It may be associated with anxiety or obsessive-compulsive traits, but a primary psychiatric disorder is unlikely.

Treatment requires a highly motivated patient and includes unpleasant-tasting nail preparations, occlusive dressings, behavioural therapy or bribery!

Ingrown toenails

Patients with an ingrown toenail are frequently encountered in general practice. It is a painful condition, due to the penetration and irritation of the soft tissues of the lateral nail fold by an irregular spicule of the lateral nail plate.

Predisposing factors include poorly fitting shoes, incorrect nail trimming, hereditary imbalance between the width of the nail matrix and nail bed, and oral retinoids.

In mild early disease (stage 1), conservative measures such as soaking the foot in warm water, use of topical or oral antibiotics, proper nail-trimming technique and elevation of the corner of the nail can be enough.

Stage 2 disease is characterised by worsening of symptoms, drainage and infection, and can be managed conservatively or surgically. Stage 3 disease is characterised by lateral wall hypertrophy and is best treated with partial nail avulsion, lateral matricectomy and destruction of the lateral wall granulation tissue. Chemical matricectomy with phenol is effective, but surgical matricectomy may offer more controlled tissue destruction and less postoperative drainage.

Trauma is a factor in many other nail conditions discussed here, including onycholysis, chronic paronychia, onychomycosis and brittle nails.

CHRONIC PARONYCHIA

Chronic paronychia is a chronic inflammatory condition of the proximal nail fold and is most common in those who have their hands in and out of water and detergents. The nail cuticle is lost and there is a space between the nail fold and the nail plate. Candida species and gram-negative bacteria are commonly cultured here and seem to aggravate the condition. Skin disease affecting nail folds, such as psoriasis, eczema and perniosis, may also contribute.

Treatment

1. General measures include keeping the hands away from soaps and detergents, and wearing gloves where possible. Any contributing skin disease should be treated.
2. Miconazole tincture may be applied twice daily to the space between the nail fold and the nail plate.
3. Nystatin ointment, when hands have to be in water.
4. Topical steroid ointment applied to the proximal nail folds has been shown to be the most effective treatment for this condition.

With treatment the prognosis is good.

ONYCHOLYSIS

Onycholysis—the separation of the nail from its bed—is one of the most common nail conditions. It is found in psoriasis, thyroid disease, yellow nail syndrome and many other conditions, but in a large number of cases no specific cause is found. It is possible that acute trauma initiates it, and once the nail is loosened, repeated minor traumas and secondary infection perpetuate the problem.

Secondary infection may be by yeasts or bacteria. Pseudomonas aeruginosa is common and produces green, blue and black discolouration. The exposed nail bed can become covered in keratin, making reattachment unlikely.

Candida albicans is very common as a secondary agent. With time it can grow into the nail plate, preventing reattachment.

Treatment

1. The nail bed should be dried by blowing the area with a hot hair dryer several times a day.
2. Anti-infective agents such as miconazole lotion or 15% sulfacetamide lotion may be applied under the nail plate.
3. If Pseudomonas is present, white vinegar soaks for 10–20 minutes twice a day are recommended (10% white vinegar in water).
4. If C. albicans is grown from the nail plate, oral treatment with ketoconazole, fluconazole or itraconazole can be very helpful. Three to six months of treatment is often needed, so monitoring of liver function, especially for ketoconazole, is recommended. Terbinafine (Lamisil®) is of no use for this condition.

BRITTLE NAILS

Brittle nails are a reasonably common problem, primarily of cosmetic significance. Clinically there are two alterations to the nail plate: excessive onychorrhexis (longitudinal ridging) and onychoschizia (horizontal layering of the distal nail plate, like the ‘split ends’ of hair).

Causes

Many factors are associated with brittleness, but water is probably the most important. Repeated wetting and drying has been shown to lead to the above changes. Other chemicals, cement, detergents and alkalis can also lead to dissolution of intercellular adhesive factors and thus to brittle nails.

There are many systemic causes listed, but these are rare. Most people with brittle nails think they must be low in calcium but there is little calcium in the nail and it does not contribute to nail hardness.

Treatment

1. Moisture and trauma should be avoided by wearing cotton and rubber gloves.
2. Oral biotin has been shown in some studies to help. Use Blackmore’s hair and nail vitamins or Tricusil® twice a day, as these contain 2.5 mg of biotin, the required daily amount.
3. Nail moisturisers such as 10% urea creams are probably better for the nails than nail hardeners. Alpha-hydroxy acids may also be effective (e.g. lactic acid, glycolic acid creams).

TRACHYONYCHIA (ROUGH NAILS)

Roughness of the nail surface implies disease of the nail matrix. Lichen planus is probably the most common cause, along with alopecia areata and twenty nail dystrophy. In lichen planus, nail changes occur in about 10% of cases but are usually mild and transient. Longitudinal ridging (onychorrhexis) is common along with the roughening. Severe atrophic disease is less common, but devastating when it happens. Scarring can occur between the proximal nail fold and the nail plate. This scar is called a pterygium.

Twenty nail dystrophy of childhood is a benign, self-limiting condition with no scarring. Some believe it to be a variant of lichen planus. The child is born with normal nails; then, at a variable age, roughness and ridging of all the nails develop. There are no hair or skin abnormalities. Complete resolution normally occurs after a number of years. In alopecia areata, nail changes again occur in about 10% of cases. Pitting is the most common abnormality, but trachyonychia is not uncommon. Most severe cases are associated with severe alopecia.

Treatment

Treatment is often unnecessary. In more severe cases, treatment is by fluorinated steroids with or without occlusion. In lichen planus with severe atrophy or early pterygium formation, the diagnosis should be confirmed by biopsy and oral steroids should be used to prevent scarring. This is as close as we come to a nail ‘dermatological emergency’.

SINGLE NAIL DEFORMITY

When a single abnormal nail develops in the absence of a history of trauma, one should think of a tumour. Myxoid or mucous cysts (due to collagenous degeneration of the extensor tendon) are the most common cause. There may be a swelling in the proximal nail fold, and a linear depression in the nail plate develops.

Other benign tumours include warts (usually obvious), subungual exostoses and glomus tumours (usually painful). Malignant tumours are less common (Bowen’s disease, squamous cell carcinoma, melanoma) and present as slowly progressive lesions with destruction of the nail.

Diagnosis often requires surgical exploration (after X-ray), and treatment is by surgical excision.

PIGMENTED BANDS

Longitudinal brown or black bands are relatively common in darker skinned races, but melanoma of the nail still needs to be excluded. Multiple bands that are light in colour and even are usually not of concern.

Trauma leading to a subungual haematoma can cause black staining of the nail bed. Usually the patient remembers trauma, but sometimes in the big toenails trauma from footwear causes bleeding under the nails of which the patient is unaware.

The main problem, however, is whether a single linear pigmented band is caused by a benign naevus, melanocytic hyperplasia of the nail matrix or malignant melanoma. Certain features favour the last:

• one finger only involved
• periungual spread of pigment
• extension of pigment to the free edge of the nail
• darkening with time
• progressive widening of the band, with blurring of the border
• age over 50 years.

Diagnosis

Any suspicious lesion should be biopsied. The proximal nail fold is reflected and the most proximal part of the pigmented band needs to be biopsied, with either a punch or a shave biopsy.

SYSTEMIC DISEASE

KOILONYCHIA

Koilonychia, or spoon-shaped nail deformity, is relatively common, and is only rarely due to iron deficiency anaemia. Most cases are idiopathic or due to chemical trauma. Paradoxically, it can occur in haemochromatosis. In childhood it is a common physiological variant that usually resolves spontaneously.

HALF-AND-HALF NAILS

In this condition there is pallor of the proximal half of the nail plate and erythema of the distal half. This is characteristically seen in renal failure. It can also occur in cardiac or hepatic failure, or with no obvious cause, and the reason for the changes is not clearly understood.

CLUBBING

The characteristic features of clubbing are increased nail plate curvature in both directions, and soft tissue hypertrophy of the digital pulp and nail bed dermis. It is usually gradual in onset, and painless, except in association with carcinoma of the lung. Schamroth’s sign is the loss of the diamond-shaped window between apposing nail plates of the corresponding left and right fingers.

Eighty per cent of cases are associated with pulmonary disease, especially chronic infections and cancers.4 Other associations include endocarditis, bowel diseases, Graves’ disease and systemic lupus erythematosus.

BEAU’S LINES

Joseph Beau first described transverse grooves in the nail plate in 1846 as a manifestation of typhoid and other acute systemic diseases. The classic description refers to transverse grooves appearing in all nails 4–8 weeks after the acute illness, They are due to disruption of matrical activity resulting in focal thinning of the nail plate. As well as systemic illness, Beau’s lines can be caused by drugs.

If one nail is involved, there has usually been some traumatic event involving the proximal nail fold and/or cuticle (paronychia). In severe cases the nail may be shed (onychomadesis).

YELLOW NAIL SYNDROME

Yellow nail syndrome is an interesting but rare condition in which slow-growing yellow nails develop in association with lymphoedema and/or chronic infective lung disease. The nail disease may precede the other manifestations by many years.

Treatment is of the underlying disease, if one is found. Otherwise vitamin E 800 units a day for 12–18 months has been reported to help.4 Oral zinc has been reported to be useful in one case.4

NAIL CARE

The aesthetic value of nails is as important today as their functional value. The ratio of the length to the breadth of the nail is considered important to its appeal—this should be about equal for the thumb, slightly more for the other nails. Everyone grooms their nails; this may be cleaning and cutting only. Some, especially women, do much more. There are many products available to enhance the appearance of nails, but little data on the efficacy of the products—only adverse reactions are reported.

Most nail manicurists soak the nails before trimming them in an arc fashion. This is probably acceptable for fingernails, but toenails should be cut straight across, to prevent ingrowing of the side of the nail into the lateral nail fold. Filing rather than cutting is less likely to cause shearing and fracturing of the nail plate. The cuticle should never be removed or traumatised, as this removes the water-tight barrier that protects the nail matrix. Unfortunately, manicurists often seem to want to do this, as the cuticle interferes with application of nail polish!

The nail plate is then groomed. This may be just with a cream containing finely ground pumice, talc or kaolin, with wax to increase the shine.

Nail polish consists of pigments suspended in a volatile solvent to which film-formers have been added. The most popular resin used is toluene sulfonamide formaldehyde, which is a cause of allergic contact dermatitis, often manifesting as eyelid dermatitis. Hypoallergenic nail enamels are available, with alternative resins. Pigments are either dissolved or suspended in the lacquer; dissolved pigment is more likely to cause staining of the nails.

Dibutyl phthalate (DBP), a chemical used to keep nail polish from chipping, has been associated with breast cancer in laboratory animals, as well as long-term fertility issues in newborn boys—leaving the cosmetics industry in a heavy debate over whether to continue use of the ingredient. The European Union banned the use of DBP in 2004 and several manufacturers have removed it, or plan to remove it, from their polishes. Toluene-free and DBP-free nail polishes are available.

Apart from reactions to the polish itself, harmful effects can come from nail polish removers, which can cause trachyonychia.

NAIL HARDENERS

Nail hardeners are basically nail polish with different solvent and resin concentrations to make the nail plate less porous. Paradoxically, their prolonged use can make nails more brittle.

NAIL MOISTURISERS

Nail moisturisers are creams and lotions that contain occlusives such as petrolatum and lanolin, or humectants such as glycerine. They can be very useful for brittle nails.

PRE-FORMED ARTIFICIAL NAILS (FALSE NAILS)

Artificial nails are plastic devices glued onto ‘normal’ nails to make them look longer and more beautiful. The nail plate is roughened by a file to increase adhesion, and a glue, usually ethyl cyanoacrylate, is used. This may cause allergic contact dermatitis, so these nails should not be worn for more than 48 hours at a time.

SCULPTURED NAILS

Sculptured nails are created with the combination of a liquid monomer and a powder polymer cured at room temperature with an organic accelerator. The paste is moulded onto the nail and held in place until it hardens, then the nail is clipped and filed into shape. As the nail grows out, the gap between the acrylic nail and the proximal nail fold must be filled.

Contact dermatitis can occur due to the monomer, now usually ethyl methacrylate.

GEL NAILS

Gel nails are applied in a semi-liquid form onto the ‘normal’ nail, then cured with ultraviolet light. Allergic reactions to these compounds are frequently reported, causing onycholysis and paronychia.

One of the problems with having beautiful polished, false or sculptured nails is that the wearer wants to keep them long, making them a repository for bacteria. Medical personnel and those in the food handling areas are discouraged from having long or false nails at work.

Despite the numerous reports of negative outcomes from nail grooming, the industry is booming and there must be more positive than negative stories. Nail adornment can be extremely useful for people with damaged, absent, diseased or ragged nails. It is wrong to dismiss complaints of unattractive nails as too trivial!

RESOURCES

Baran R, Dawber R, de Berker D, et al. Baran & Dawber’s diseases of the nails and their management, 3rd edn. Oxford: Blackwell Science, 2001.

Baran R, Barth J, Dawber R, et al. Nail disorders: common presenting signs, differential diagnosis and treatment. New York: Churchill Livingstone, 1991.

REFERENCES

1 Haneke E. Achilles foot-screening project: background, objectives and design. J Europ Acad Dermatol Venereol. 2006;12(S1):S2-S5.

2 Roseeuw D. Achilles foot-screening project: preliminary results of patients screened by dermatologists. Eur Acad Dermatol Venereol. 2006;12(S1):S6-S9.

3 Gill D, Marks R. A review of the epidemiology of tinea unguium in the community. Aust J Dermatol. 2002;40(1):6-13.

4 Tosti A, Piraccini BM, Mariani R, et al. Are local and systemic conditions important for the development of onychomycosis? Eur J Dermatol. 1998;8(1):41-44.

5 Baran R, Dawber R, de Berker D, et al. Baran & Dawber’s diseases of the nails and their management, 3rd edn. Oxford: Blackwell Science, 2001.

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