What is nail psoriasis?
Psoriatic nail dystrophy mainly occurs in patients whom also suffer from psoriasis of the skin. Less than 5% of patients have solely psoriasis of the nails. It is commonly (53-86%) seen in patients with psoriatic arthritis especially when the arthritis affects the fingers and toes.
What are the signs and symptoms?
The nail unit is made up of several parts; nail plate, nail bed, hyponychium, nail matrix, nail folds, cuticle, anchoring portion of the nail bed, and distal phalangeal bones. Signs of nail psoriasis vary according to the part of the nail affected and the nature of the deformity.
|Oil drop or salmon patch||Nail bed||Translucent yellow-red discoloration in the nail bed, resembles drop of oil under nail plate|
|Pitting||Proximal nail matrix||Loss of parakeratotic cells from surface of nail plate|
|Beau's lines||Proximal nail matrix||Transverse lines in nails due to intermittent inflammation causing growth arrest lines|
|Leukonychia||Midmatrix disease||Areas of white nail plate due to foci of parakeratosis within the body of the nail plate|
|Subungual hyperkeratosis||Hyponychium and nail bed||Excessive proliferation of the nail bed and hyponychium. May lead to onycholysis.|
|Onycholysis||Nail bed and hyponychium||Nail plate separates from its underlying attachment to nail bed. Nail plate whitens and may detach. Secondary infection may occur.|
|Nail plate crumbling||Nail bed or nail matrix||Nail plate weakens due to disease of underlying structures|
A nail biopsy is occasionally needed to confirm the diagnosis of nail psoriasis as some other nail disorders may look similar.
What treatment is available?
There is no cure for nail psoriasis but it may improve by itself and may even return to a normal appearance. Although nail psoriasis is a benign condition, it can be uncomfortable and look unsightly causing significant dysfunction and psychological distress.
Several treatment options are available. Currently no one option has been identified as the best and all of them may prove disappointing. Treatment depends on the site and severity of the nail disease in individual patients.
- Calcipotriol solution applied twice daily to the nail folds is safe to use and may help nail psoriasis if applied over prolonged periods
- Topical high-potency corticosteroid solution or ointment works best when covered by cellophane wrap at bedtime. Avoid prolonged occlusion (2 weeks at most) or continuous therapy with corticosteroids. Longterm, it may be applied as weekend pulses i.e., on two consecutive days per week.
- Intralesional triamcinolone acetonide injected into proximal nail folds is helpful (but painful) in nail matrix psoriasis.
- Topical 5-fluorouracil cream applied to the matrix for 6 months may improve pitting and subungual hyperkeratosis.
- Psoralen and UVA (photochemotherapy or PUVA) may improve nail psoriasis.
- Systemic treatment with oral methotrexate, retinoids, ciclosporin and biologics is usually prescribed for generalised psoriasis but may also be helpful for nail disease.
- Antifungal treatment may be prescribed if secondary infection is present.
- Chemical or surgical avulsion therapy, i.e. complete removal of the nail, is rarely recommended. The regrowing nail may be as badly or worse affected than prior to the procedure.
Textbook of Dermatology. Ed Rook A, Wilkinson DS, Ebling FJB, Champion RH, Burton JL. Fourth edition. Blackwell Scientific Publications.
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