NAIL PSORIASIS

 

Psoriasis can be limited to the nails and produce nail signs that mimic those of a large number of other nail disorders. Pitting is considered by dermatologists to be the typical symptom of psoriasis. Psoriatic pits are limited to the fingernails, are large, deep, and irregular , and represent psoriatic involvement of the proximal nail matrix.

Onycholysis, salmon patches, and subungual hyperkeratosis are additional clinical signs of nail bed psoriasis. Onycholysis is actually the most common manifestation of nail psoriasis and may affect both fingernails and toenails. In fingernails the presence of an erythematous border along the onycholytic area is diagnostic for nail psoriasis . In toenails onycholysis is usually combined with subungual hyperkeratosis and may closely resemble onychomycosis.

 

 

NAIL PSORIASIS AT A GLANCE

·         Present in up to 50 percent of patients with skin psoriasis and up to 83 percent of those with psoriatic arthritis.

·         Isolated nail psoriasis is not rare.

·         Nail matrix and nail bed are most commonly affected.

·         Most often precipitated or worsened by trauma.

·         Most common signs are onycholysis, salmon patches, subungual hyperkeratosis, and irregular pitting.

·         Fingernails and/or toenails may be affected. Several nails are involved in most cases.

·         Treatment is often unsatisfactory.

Salmon patches (oil drop sign) are also diagnostic for nail psoriasis. They are seen in fingernails and appear as yellow-red areas of discoloration in the center of the nail or bordering an onycholytic area . Rarely, nail psoriasis may produce severe nail plate abnormalities such as trachyonychia or crumbling. Other common but rather aspecific signs include splinter hemorrhages and paronychia.

 

Treatment

Treatment of psoriasis affecting only the nails is often unsatisfactory and should be limited to patients who experience functional impairment or severe cosmetic problems. It is important to instruct patients to avoid trauma and to refer the patient to a rheumatologist if digital pain is described.

Systemic treatments for skin and joint psoriasis are generally effective for nail psoriasis (methotrexate, cyclosporin A, biologics). Phototherapy is not effective.

Intralesional steroids (triamcinolone acetonide 2.5 to 5.0 mg/mL in saline) are the best treatment for nail matrix psoriasis limited to a few fingernails, for which they can be injected in the proximal nail fold every 4 to 8 weeks. Acitretin at low dosages (0.3 mg/kg/day) for 4 to 6 months may also be an effective option in severe nail psoriasis. In nail bed psoriasis, topical treatment with calcipotriol or tazarotene reduces subungual hyperkeratosis.

 

Differential Diagnosis of Nail Psoriasis

·         Onycholysis

·         Onychomycosis (usually associated with subungual hyperkeratosis): up to 21% of psoriatic nails have secondary onychomycosis

·         Idiopathic onycholysis (fingernails): usually seen with other nail changes

·         Trauma (toenails): psoriasis usually affects several nails, not just halluces

·         Pitting

·         Eczema: often has periungual scaling and Beau's lines

·         Alopecia areata: different morphology of pits