Dermatophyte, mold, and candida infections of the nails are common causes of nail disorders. They closely resemble other nails disorders such as psoriasis. Fungal infections of the nails are covered in Chapter 10.
Bacteria can also infect the nail unit. Pseudomonas is a common colonizer of onycholytic nails.2 The affected nail is usually discolored green or black (Figure 20-2). Patients often have a history of wet-work. Bacterial cultures of pus or nail clippings can confirm the diagnosis. Treatment involves trimming the onycholytic portion of the nail and the use of one of the following topical therapies: soaking affected nails 2 to 3 times a day in a dilute bleach solution (2% sodium hypochlorite) or half-strength vinegar, solution; and application of polymyxin B, chlorhexidine solution, 15% sulfacetamide, gentamicin or chloramphenicol ophthalmological solution or octenidine dihydrochloride 0.1% solution for 4 weeks or until resolved.2,3 Systemic antibiotics should not be administered unless there are signs of cellulitis.
Onycholysis with pseudomonas colonization. Green discoloration of the undersurface of nail plates.
Psoriasis is a common cause of nail disease. Patients often report a personal or family history of psoriasis. Patients with nail involvement are more likely to have psoriatic arthritis, so it is important to ask about a history of joint pain. Nail psoriasis significantly impacts patients' quality of life with pain and negative impact on activities of daily living, professional activities, and housework.4 Severe nail psoriasis is associated with a higher risk of depression and anxiety.4 Psoriasis of the nails commonly presents with pitting, onycholysis, subungual debris, and discoloration (Figure 20-3). The nails will usually be negative for fungal elements with examination of a potassium hydroxide (KOH) preparation; however, psoriatic nails can be secondarily infected with a dermatophyte. Punch biopsy of an involved area of the nail unit (nail bed or matrix) can confirm the diagnosis.5 Treatment of nail psoriasis is challenging. High-potency topical corticosteroids (betamethasone or clobetasol) with or without vitamin D analogues (calcitriol or calcipotriol) can be used. For nail matrix lesions, these medications should be applied to the proximal nail fold. For nail bed lesions, the onycholytic nail should be trimmed back and the medications should be applied to the nail bed. Tazarotene gel 0.1% applied at bedtime to involved nail plates may improve onycholysis and pitting.1
Psoriasis. Nail pits, onycholysis, and "oil drop" with psoriatic plaque on nail folds.
Nail lichen planus commonly occurs in isolation without any evidence of skin or mucosal lichen planus, but about 10% of patients with mucosal membrane or skin lichen planus also have nail involvement.2,5 Nail lichen planus usually has an abrupt onset with longitudinal ridging, thinning, and fissuring of the nail plate (Figure 20-4). Pain may be present.2 Biopsy may be necessary for diagnosis in the absence of skin or mucous membrane findings. Early treatment may avert the possibility of pterygium formation. Once present, a pterygium is permanent and will not respond to any treatment. First-line treatment for nail lichen planus is systemic or intralesional corticosteroids.2 Systemic retinoids can also be used.5 There are reports of success with topical tacrolimus6 and a combination of topical tazarotene and clobetasol under occlusion.7
Lichen planus. Longitudinal ridging and thinning of nail plate with early pterygium formation.
Beau's Lines appear after a disruption of nail formation in the matrix. They present as horizontal, depressed, white, nonblanching, bands of the nail plate (Figure 20-5). The depth of the line corresponds to the severity of damage, and the width corresponds to the length of exposure.8 One can usually elicit a history of major systemic stress due to illness, surgery, accident, or history of exposure to a causative medication. Associated medications include chemotherapeutic medications and systemic retinoids.8 No treatment is necessary since the lines will resolve when the affected nail plate grows out. However, the lesions will continue to occur with repeated administration of causative medications or repeated illness.
Beau's lines. Horizontal, depressed bands on toenails with separation of nail plate on great toenail in a patient following pneumonia.
Yellow nail syndrome is commonly seen as part of a triad with lung disease and chronic lymphedema. Most patients are between the fourth and sixth decades of life, but cases have been reported in children and infants.9 It can also be associated with rheumatoid arthritis, chronic obstructive pulmonary disease, bronchiectasis, chronic bronchitis, sinusitis, carcinoma of the larynx and other malignancies, and thyroid disease. Yellow nail syndrome may be inherited or congenital.2 Patients may have a history of associated conditions, or a family history of the syndrome. Examination shows diffuse yellow-colored, thickened nail plates with excessive curvature of the nails, or a slow rate of nail growth. All nails are affected.2 Nail disease will sometimes resolve with treatment of the underlying condition.2
Nail involvement in alopecia areata is present in up to 50% of children and 20% of adults.2 Extensive nail involvement correlates with more severe hair loss, and a poorer prognosis.10–12 The nail changes can precede, occur concomitantly, or occur after hair loss.2,10 Rarely, nail changes can be the only finding in alopecia areata.5 Superficial, regular, geometric pitting is most common (Figure 20-6). This pitting is much more regular than pitting due to psoriasis.2,10 Geometric punctate leukonychia can be seen as regularly spaced, small, white spots on the nail plate.2 Trachyonychia (sandpaper-like nails) can occur. Nonspecific findings may include Beau's lines, onychomadesis (shedding of the nail plate), onychorrhexis (brittle nails), thinning or thickening of the nail plate, spoon nails, and red lunulae.2,10 Biopsy of the matrix is usually not necessary, but if done will show spongiosis and a lymphocytic infiltrate of the proximal nail fold, nail matrix, nail bed, and/or hyponychium.5 Oral or intralesional corticosteroids may improve the nail disease.2,5 There is a report of successful treatment with topical tazarotene.13
Nail pits in a patient with alopecia areata. Superficial pitting in a geometric pattern.
20-Nail dystrophy (trachyonychia) is most commonly caused by alopecia areata, and can affect 1 to 20 nails. It can also be caused by atopic dermatitis, ichthyosis vulgaris, lichen planus, or psoriasis, and can be an isolated finding in childhood.2,5,11 Nails have a roughened surface, with longitudinal ridging and thinning and are classically described as having a sandpaper appearance. There are no nail findings that distinguish trachyonychia due to alopecia areata, lichen planus, or psoriasis.2 However, abnormalities suggestive of lichen planus, psoriasis, or alopecia areata may be present on the skin and help with diagnosis. Longitudinal nail biopsy can help determine the underlying disorder; however, it is not usually recommended for this relatively benign condition.14 The condition usually resolves on its own in a few years when not associated with other skin diseases.5 Topical tazarotene has been reported to be useful.13
Habit tic deformity occurs with manipulation of the proximal nail fold. Patients may or may not admit to picking, rubbing, or scratching the proximal nail fold or cuticle, but often will absent-mindedly pick at their cuticles during the office visit. The lesions are roughly parallel, horizontal depressions most often over the median nail plate (Figure 20-7). There may also be an absent cuticle, and a widening of the cuticular sulcus. Behavior modification is the most effective treatment. Manipulation of the nail fold should be minimized, by occluding with bandages if necessary.15 The condition may be successfully treated with selective serotonin reuptake inhibitors or other therapies used to treat obsessive–compulsive disorders.16 Cyanoacrylate adhesive (superglue) applied to the proximal nail fold 1 to 2 times weekly, to mimic the cuticle and seal the sulcus, has also been reported to be effective. This acts as a barrier to manipulation. Patients should be warned of the potential to develop allergic contact dermatitis to the adhesive.15
Habit tic deformity. Parallel horizontal depressions over the medial nail plate caused by chronic rubbing of the cuticle.
Simple onycholysis is not due to any underlying medical disorder. The separation usually starts distally, but can start proximally. The detached nail plate appears white due to air between the nail plate and nail bed (Figure 20-8). It is more common in women and adults. The longer the condition persists, the less likely it is to resolve. Patients may have a history of exposure to irritants (eg, nail cosmetics, soaps), or physical trauma.17 The most common causes of toenail trauma are ill-fitting shoes, sports-related trauma, long nails, and stubbing the toe.17 Common causes of fingernail trauma include hitting the nail plate with a tool or squeezing the nail plate in a door, and vigorous cleaning under the nail. Onycholysis can also be associated with taxane chemotherapy and other oral medications.8 Photo-onycholysis may be associated with the tetracyclines, particularly doxycycline and exposure to UV light.8
Onycholysis. Chronic irritant dermatitis on nail folds from dish detergent with onycholysis of nail plate.
If a secondary infection with pseudomonas, mold, or yeast is present the nail can appear green or brown.17 Candida is cultured more than 80% of the time, but is likely just a colonizer, as treatment with systemic antifungals does not cure onycholysis.17 If reattachment does not occur, the nail bed will eventually cornify and produce dermatoglyphics like the rest of the digit. If this occurs, the nail plate will no longer attach to the nail bed.
Secondary onycholysis is caused by an underlying nail disorders such as psoriasis, lichen planus, and onychomycosis or systemic diseases such as hyperthyroidism and porphyria. Tumors of the nail bed can also cause onycholysis.
Management involves minimizing nail trauma. The patient should be instructed to keep the detached portion of their nails trimmed back until the nail is reattached. They should not vigorously clean the area under the detached nail as this can cause further detachment. Patients should wear gloves for dry and wet work. They should not use any cosmetic nail products.17 Wearing shoes with low heels and a wide toe box is also recommended.
A topical antiseptic, such as thymol 4% solution, can be applied to the exposed nail bed to prevent infection.