Definition

Nail psoriasis, also known as psoriatic nail dystrophy, is a manifestation of psoriasis affecting the nail bed, nail matrix, or both. It presents specific and non-specific clinical changes, including pitting, onycholysis, subungual hyperkeratosis, and nail discoloration. Nail involvement is often associated with psoriatic arthritis and can significantly impact quality of life due to pain, functional limitations, and psychological distress.

Epidemiology

Nail psoriasis occurs in 10–90% of psoriasis patients, with higher prevalence in adults compared to children. It often coincides with skin or joint psoriasis but may also present as the sole manifestation of the disease. Up to 80–90% of patients with psoriatic arthritis exhibit nail changes. Although nail psoriasis affects all ages and sexes, a slight male predominance has been noted. Severe or chronic plaque psoriasis increases the likelihood of nail involvement.

Etiology

Nail psoriasis arises from psoriatic inflammation in the nail matrix or nail bed:

Matrix involvement causes pitting, leukonychia, red spots in the lunula, and nail crumbling.
Nail bed involvement leads to oil-drop discoloration, onycholysis, subungual hyperkeratosis, and splinter hemorrhages.

Theories on etiology include dysregulated immunity (e.g., IL-10 expression), trauma (Koebner phenomenon), and secondary infections like onychomycosis. Genetic factors, such as the HLA-Cw6 allele, contribute to cutaneous psoriasis but may differ in nail disease.

Clinical Features

Nail psoriasis can affect fingernails, toenails, or both, and patients often experience pain, tenderness, and difficulty with fine motor tasks. Common manifestations include:

Matrix-related changes:

– Pitting (punctate depressions)

– Leukonychia (white discoloration)

– Red spots in the lunula

– Nail crumbling

Nail bed-related changes:

– Oil-drop discoloration or salmon patches

– Onycholysis (distal nail separation)

– Subungual hyperkeratosis (keratin accumulation)

– Splinter hemorrhages

Severe cases may involve all 20 nails, with additional complications like paronychia and acrodermatitis continua of Hallopeau.

Diagnosis

Diagnosis is primarily clinical, especially in patients with cutaneous psoriasis or psoriatic arthritis. The Nail Psoriasis Severity Index (NAPSI) helps quantify disease severity. Fungal infections (onychomycosis) must be ruled out through microscopy or culture, as they can mimic or exacerbate nail psoriasis. In rare cases, a proximal nail matrix biopsy is needed to confirm the diagnosis or exclude malignancy, though this may cause permanent nail deformity.

Management

Treatment depends on severity:

Mild Disease

– Topical corticosteroids (e.g., betamethasone, clobetasol)

– Vitamin D analogs (e.g., calcipotriol)

– Combination therapies

Moderate to Severe Disease

– Systemic treatments:

– Methotrexate

– Acitretin

– Biologics (e.g., infliximab, adalimumab, ustekinumab)

– Small molecules (e.g., apremilast, tofacitinib)

– Non-pharmacologic interventions: Phototherapy ,Laser treatments.

General Measures:

– Minimize nail trauma and keep nails short.

– Address coexisting onychomycosis before initiating psoriasis treatments.

Written by:

Raneem Alahmadi, Medical Intern

Revised by:

Naif Alshehri, Medical Intern

Resources:

Bologina 5th edition

Dermnet

UTD