Nail psoriasis affects up to 50% of patients with cutaneous psoriasis and is a strong risk factor for psoriatic arthritis (PsA). Matrix involvement causes pitting, leukonychia, crumbling; nail bed involvement causes onycholysis, oil-drop (salmon) patches, and subungual hyperkeratosis. Disease impacts function and quality of life. Therapy depends on severity, number of nails, and associated skin/PsA. Options range from topical high-potency steroids/vitamin D analogs to intralesional corticosteroids and systemic/biologic therapies that also address skin and joint disease.
Epidemiology and Associations
- Occurs in all ages; more frequent and severe with longer psoriasis duration.
- Strong association with enthesitis and distal interphalangeal (DIP) PsA; nail disease can precede joint symptoms.
Pathophysiology
- Inflammation of nail matrix and bed related to psoriatic pathways (Th17/IL-23 axis).
- Enthesis-organ concept: nail unit and DIP enthesis are anatomically/functional linked.
Clinical Features
- Matrix signs: pitting (irregular, coarse), crumbling, Beau lines, leukonychia, red lunula.
- Bed signs: oil-drop discoloration, onycholysis with erythematous rim, subungual hyperkeratosis, splinter hemorrhages.
- Severity scoring: NAPSI (Nail Psoriasis Severity Index).
Differential Diagnosis
- Onychomycosis, eczema, lichen planus (longitudinal ridging, pterygium), trauma, alopecia areata nails (regular pits), reactive arthritis, chronic paronychia.
- Fungal coinfection is common; obtain KOH/culture/PAS before systemic therapy.
Management
- General measures
- Keep nails short; avoid trauma/repetitive wet work; protective gloves; manage paronychia; treat coexistent tinea.
- Topical therapy (mild, few nails)
- High-potency corticosteroids (clobetasol) solutions/ointments under occlusion; nail lacquers.
- Vitamin D analogs (calcipotriol) alone or with steroids (weekend steroid/weekday calcipotriol).
- Tazarotene 0.1% gel for pitting/onycholysis; combine with steroid to reduce irritation.
- Tacrolimus 0.1% ointment for periungual dermatitis.
- Intralesional therapy (moderate, resistant few nails)
- Triamcinolone acetonide 2.5–10 mg/mL injected into matrix or nail bed every 6–8 weeks; requires experience; pain mitigation with digital block/ice; monitor for atrophy.
- Phototherapy and devices
- Targeted phototherapy (308 nm excimer) for periungual lesions; evidence modest.
- Laser for onycholysis hyperkeratosis has limited data.
- Systemic therapy (moderate–severe nail disease, multiple nails, functional impairment, or concomitant skin/PsA)
- Conventional: methotrexate, cyclosporine, acitretin (retinoid particularly for hyperkeratosis; teratogenic; mucocutaneous AEs).
- Biologics with robust nail data:
- Anti-TNF: adalimumab, infliximab, etanercept.
- Anti-IL-17: secukinumab, ixekizumab, brodalumab.
- Anti-IL-23: guselkumab, risankizumab, tildrakizumab.
- JAK inhibitors (tofacitinib, upadacitinib) show benefits in PsA with nail involvement.
- Choice guided by comorbidities, PsA presence, patient preference, and access.
- Monitoring and outcomes
- Expect slow improvement due to nail growth: fingers ~6 months, toes 12–18 months.
- Use NAPSI or photographic tracking; screen for PsA symptoms regularly (DIP pain, morning stiffness, swelling, dactylitis); refer to rheumatology when indicated.
Prognosis
- Chronic with flares; significant improvements achievable with modern systemic/biologic therapy, especially when PsA is treated concurrently.
- Recurrence with trauma (“Koebnerization”) common; maintenance needed.
References (recent guidelines and key reviews)
- Nail psoriasis consensus and treatment algorithms, 2022–2024.
- Biologic trials reporting NAPSI outcomes, 2021–2024.
- Studies on nail–enthesis–PsA relationships, 2021–2024.