What is the diagnosis and management for an adult patient with irregular white discoloration and pitting at the tip of all fingernails, potentially indicating an underlying condition such as psoriatic nail disease or eczema?

Psoriatic Nail Disease (Psoriatic Onychodystrophy)

The combination of irregular white discoloration and pitting affecting all fingernails is most consistent with psoriatic nail disease, which requires evaluation for psoriatic arthritis and treatment based on functional impairment and quality of life impact. 1

Diagnosis

Nail psoriasis occurs in approximately 50% of all psoriasis patients and up to 90% of patients with psoriatic arthritis. 1 The clinical presentation described—pitting combined with white discoloration at the nail tips—represents involvement of both the nail matrix (pitting) and nail bed (leukonychia/white discoloration). 1

Key Diagnostic Features to Confirm

• Nail matrix involvement produces pitting, leukonychia (white spots), red lunula, and nail plate dystrophy 2
• Nail bed involvement causes onycholysis (nail separation), oil-drop sign (salmon patches), splinter hemorrhages, and subungual hyperkeratosis 1, 2
• All fingernails affected suggests systemic inflammatory disease rather than localized trauma or infection 1

Critical Evaluation Steps

• Screen for psoriatic arthritis immediately: Ask about early morning stiffness lasting >30 minutes, joint pain, or swelling—particularly in distal interphalangeal joints 1
• Examine skin thoroughly for psoriatic plaques on scalp, elbows, knees, gluteal cleft, and other typical locations 1
• Rule out onychomycosis: While 50% of dystrophic nails are non-fungal, laboratory confirmation with microscopy and culture is mandatory if fungal infection is suspected, as clinical appearance alone is unreliable 3
• Distinguish from other causes: Lichen planus, trauma, and eczema can mimic psoriatic nails but typically lack the specific combination of pitting with white discoloration across all nails 1, 3

Management Algorithm

Assess Disease Severity and Impact

Use the modified Nail Psoriasis Severity Index (mNAPSI) to grade severity and the Nail Psoriasis Quality of Life Scale (NPQ10) to evaluate functional impairment. 4 Nail psoriasis represents a significant therapeutic challenge and correlates with more severe disease, earlier onset, and higher risk of psoriatic arthritis. 1, 2

Treatment Selection Based on Severity

For isolated nail disease with minimal functional impairment:

• Topical corticosteroids applied to the nail matrix and bed 4, 5
• Keep nails trimmed short and avoid trauma 5
• Patient education on proper nail care to minimize further damage 6

For moderate nail disease or when topical therapy fails:

• Intralesional corticosteroid injections into individual severely affected digits 4, 5
• Note: This approach is limited by pain and requires focused treatment 5

For severe nail disease causing significant functional impairment or quality of life reduction:

• Systemic therapy is justified when nail involvement sufficiently diminishes function and quality of life, even without widespread skin disease 5
• TNF-α inhibitors (such as adalimumab) are highly effective: In Study Ps-III, 49% of patients achieved ≥2-grade improvement and clear/minimal disease on fingernail assessment at 26 weeks, compared to 7% with placebo 7
• Adalimumab dosing: 80 mg initial dose, then 40 mg every other week starting Week 1 7
• Alternative systemic options include oral retinoids for widespread nail disease or ustekinumab for refractory cases 4

Special Considerations

If psoriatic arthritis is present or suspected:

• Immediate rheumatology referral is essential 1
• Up to 90% of psoriatic arthritis patients have nail changes, making nail disease a critical marker 1
• Left untreated, psoriatic arthritis causes progressive joint damage, severe physical limitations, and disability 1
• First-line treatment for moderate-to-severe psoriatic arthritis includes methotrexate, TNF-α blockade, or combination therapy 1

Common Pitfalls to Avoid

• Never assume fungal infection based on appearance alone—50% of dystrophic nails are non-fungal, and misdiagnosis delays appropriate treatment 3
• Don't overlook joint symptoms: Actively screen every patient with nail psoriasis for early morning stiffness and joint involvement at each visit 1
• Avoid undertreating: Nail psoriasis causing functional impairment warrants systemic therapy even without extensive skin involvement 5
• Don't ignore quality of life impact: Nail disease is physically and emotionally distressing and may significantly impair daily activities 6