NAIL PSORIASIS: A CLINICAL REVIEW OF DIAGNOSIS, DIFFERENTIAL DIAGNOSIS, AND TREATMENT

УДК 616.97

Abstract

Background: Nail psoriasis affects 50–80% of patients with cutaneous psoriasis and up to 90% of those with psoriatic arthritis, yet it remains underdiagnosed.

Objective: To provide a practical clinical overview of nail psoriasis recognition, differential diagnosis, and stepwise treatment.

Methods: Review of current evidence on pathophysiology, clinical signs, diagnostic tools, and therapies.

Results: Key signs include pitting and Beau's lines (matrix involvement) and onycholysis with subungual hyperkeratosis (nail bed involvement). Onychomycosis is the main mimicker, often coexisting. Treatment ranges from topical corticosteroids for mild cases to intralesional injections, systemic agents (methotrexate, cyclosporine), and biologics (anti‑IL‑17, anti‑IL‑23) for moderate‑to‑severe disease.

Conclusion: Early recognition and stepwise management improve outcomes. Nail psoriasis is also a predictor of psoriatic arthritis, warranting regular joint assessment.

Аннотация

Актуальность: Псориаз ногтей поражает 50–80% пациентов с кожным псориазом и до 90% пациентов с псориатическим артритом, однако он остаётся недостаточно диагностированным.

Цель: Представить практический клинический обзор по распознаванию псориаза ногтей, дифференциальной диагностике и поэтапному лечению.

Методы: Обзор современных данных о патофизиологии, клинических признаках, диагностических инструментах и методах терапии.

Результаты: Ключевые признаки включают точечные вдавления и линии Бо (вовлечение матрикса), а также онихолизис с подногтевым гиперкератозом (вовлечение ногтевого ложа). Онихомикоз является основным заболеванием, имитирующим псориаз ногтей, и часто сосуществует с ним. Лечение варьирует от топических кортикостероидов при лёгких формах до внутриочаговых инъекций, системных препаратов (метотрексат, циклоспорин) и биологических препаратов (анти-ИЛ‑17, анти-ИЛ‑23) при заболевании средней и тяжёлой степени.

Заключение: Раннее распознавание и поэтапное ведение пациентов улучшают исходы. Псориаз ногтей также является предиктором псориатического артрита, что требует регулярной оценки состояния суставов.

Keywords: Nail psoriasis, onycholysis, pitting, psoriatic arthritis, biologics, NAPSI.

Ключевые слова: Псориаз ногтей, онихолизис, точечные вдавления, псориатический артрит, биологические препараты, NAPSI.

Introduction

Nail psoriasis (psoriatic onychodystrophy) affects 50–80% of patients with cutaneous psoriasis and up to 90% of those with psoriatic arthritis [1,4]. Isolated nail psoriasis occurs in 1–5% of cases[2]. It results from IL‑23/IL‑17‑driven inflammation of the nail matrix and nail bed, producing characteristic signs: pitting, Beau's lines, and trachyonychia (matrix involvement) or onycholysis, subungual hyperkeratosis, and oil spots (nail bed involvement) [1,6]

Despite its frequency, nail psoriasis is underdiagnosed and often mistaken for onychomycosis, with which it coexists in 18–30% of cases[11]. Importantly, nail psoriasis is a strong predictor of psoriatic arthritis – nail changes may precede joint symptoms by months or years [4,5]

This clinical review provides a practical framework for diagnosis, differential diagnosis, severity assessment (NAPSI)[3], and stepwise treatment from topicals to biologics[7,9]. 

Clinical Presentation :

Nail psoriasis presents with distinct signs depending on the affected anatomical site[1,6].

Nail matrix involvement (where the nail plate is formed)[1] :

Pitting – small, shallow depressions (≥5 pits is highly suggestive)

Trachyonychia – rough, sandpaper-like nail surface

Beau's lines – transverse grooves

Leukonychia – white spots or bands

Nail bed involvement (the tissue supporting the nail plate)[1,12] :

Onycholysis – distal nail plate detachment, often with a reddish‑brown border

Subungual hyperkeratosis – chalky, yellowish-white debris under the nail

Oil spots (salmon patches) – translucent yellow‑orange discoloration

Splinter hemorrhages – thin, dark red longitudinal lines

Periungual involvement (surrounding tissues):

Erythema, swelling, tenderness (pulpitis or paronychia)

All twenty nails may be affected. Toenail involvement is often more severe due to trauma and moisture. The Nail Psoriasis Severity Index (NAPSI) quantifies severity by dividing the nail into quadrants and scoring matrix and nail bed signs separately (0–8 per nail)[3].

Differential Diagnosis :

Treatment :

Treatment is guided by the number of nails involved, severity (NAPSI score), patient preference, and presence of psoriatic arthritis[7].

Step 1 – Mild disease (1–3 nails, mild onycholysis or pitting)

Potent or very potent topical corticosteroids (clobetasol, betamethasone) – once daily, up to 6 months[12]

Topical vitamin D analogues (calcipotriol) – alone or in combination with corticosteroids[12]

Topical calcineurin inhibitors (tacrolimus) – especially for periungual inflammation

Step 2 – Moderate disease (several nails, moderate hyperkeratosis or onycholysis)

Intralesional corticosteroid injections (triamcinolone acetonide 2.5–10 mg/mL) – every 4–6 weeks, 2–3 sessions[8]

Usually reserved for fingernails; painful but effective

Step 3 – Severe or refractory disease (multiple nails, severe onycholysis/hyperkeratosis, or associated psoriatic arthritis)

Oral systemic agents: methotrexate (15–25 mg/week), cyclosporine (3–5 mg/kg/day), acitretin (0.2–0.5 mg/kg/day), or apremilast[9]

Biologics (most effective for nail psoriasis)[10] :

Anti‑IL‑17: secukinumab, ixekizumab (rapid improvement, often within 12 weeks)

Anti‑IL‑23: guselkumab, risankizumab

Anti‑TNF: adalimumab, etanercept (also effective for arthritis)

Special considerations:

Response is slow (nail growth requires months – fingernails 4–6 months, toenails 9–12 months)[1,7]

Treat coexisting onychomycosis if present

Psoriatic arthritis screening is mandatory in all patients with nail psoriasis.

Conclusion.

Nail psoriasis is a common yet underrecognized manifestation of psoriasis, affecting the majority of patients with cutaneous disease and serving as a strong predictor of psoriatic arthritis[4,5]. Early recognition of characteristic signs – pitting, onycholysis, subungual hyperkeratosis, and oil spots – allows prompt diagnosis and differentiation from onychomycosis[7]

Treatment should be stepwise: topical therapies for mild disease, intralesional corticosteroid injections for moderate involvement, and systemic agents or biologics for severe or refractory cases. Biologics targeting IL‑17 or IL‑23 offer the highest efficacy and fastest response[10]. Given that nail changes may precede joint symptoms by months or years, every patient with nail psoriasis warrants regular screening for psoriatic arthritis.

With appropriate management, significant improvement is achievable, though patience is required as nail growth takes months. Clinicians should not dismiss nail psoriasis as a mere cosmetic concern – it is a treatable condition with important prognostic implications.

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