1. Diagnosis Criteria

🔵 A. Nail Psoriasis – Diagnostic Criteria

Clinical Diagnosis (no single gold standard). Diagnosis is based on classic nail findings + history of psoriasis.

Major Nail Features

1. Pitting
2. Oil-drop (salmon patch) discoloration
3. Onycholysis with erythematous border
4. Subungual hyperkeratosis (psoriatic type: chalky, white)
5. Nail crumbling / roughness
6. Leukonychia

Supportive Features

• Current or past cutaneous psoriasis
• Psoriatic arthritis
• Family history of psoriasis
• Negative fungal studies (KOH/PAS/culture)

Diagnostic Tools

• Clinical exam = primary
• Dermoscopy (onycholysis with reddish margin, irregular pitting)
• PAS stain of nail clipping (to rule out fungus)
• Nail matrix biopsy (rarely needed)

🟢 B. Onychomycosis – Diagnostic Criteria

Must confirm fungus before systemic therapy.

Major Criteria

(At least 1 required)

1. Positive KOH (hyphae or yeast)
2. Positive fungal culture
3. Positive PAS stain (most sensitive)
4. PCR positive for dermatophyte or non-dermatophyte mold

Clinical Features

• Nail thickening (onychauxis)
• Whitish/yellowish discoloration
• Subungual debris (keratinous, dense)
• Distal-lateral subungual onychomycosis (most common)
• Proximal white onychomycosis (HIV indicator)
• Total dystrophic onychomycosis

Supportive Features

• Tinea pedis/manuum
• Household fungal infection
• Slow progression
• Usually no pitting, no oil-drop

---

2. Management

🔵 A. Management of Nail Psoriasis

1. Mild Disease (<3 nails, cosmetic concern only)

Topical therapy (first-line)

• High-potency topical steroid (Clobetasol 0.05%)
• Calcipotriol (vitamin D analog)
• Tazarotene 0.1% gel
• Tacrolimus 0.1% ointment (safe for long-term use)

2. Moderate Disease

Intralesional therapy

• Triamcinolone acetonide 2.5–10 mg/mL
  • Inject into nail matrix or nail bed every 4–8 weeks

3. Severe Disease / Multiple Nails / Functional Impairment

Systemic therapy (depending on comorbid psoriasis)

• Methotrexate 7.5–20 mg weekly
• Cyclosporine 2.5–5 mg/kg/day
• Acitretin 25–50 mg/day (great for hyperkeratosis)
• Biologic therapy (BEST evidence)
  • IL-17 inhibitors: Secukinumab, Ixekizumab
  • TNF-α inhibitors: Adalimumab, Etanercept
  • IL-23 inhibitors: Guselkumab, Risankizumab

Biologics are most effective overall for severe nail psoriasis.

4. Supportive care

• Avoid trauma & excessive manicure
• Keep nails short
• Treat concomitant fungal infection
• Moisturizers & protect hands (gloves)

🟢 B. Management of Onychomycosis

1. Confirm Diagnosis First

Systemic antifungal therapy should not be started without confirmation.

• KOH preparation – rapid bedside test
• PAS stain – highest sensitivity
• Fungal culture – identifies organism (takes longer)

Exam pearl: Helps differentiate from nail psoriasis or trauma.

2. Systemic Antifungal Therapy (First-line)

A. Terbinafine – Drug of Choice

Terbinafine (250 mg) 1×1 po pc

• Fingernails: 6 weeks
• Toenails: 12 weeks

Rationale:

• Fungicidal against dermatophytes
• Highest cure rate

Monitoring:

• Baseline liver function test (LFT)
• Repeat if prolonged therapy or symptoms

B. Itraconazole – Alternative

Pulse therapy (preferred for fingernails)

Itraconazole (100 mg) 2×2 po pc for 1 week/month

• Fingernails: 2 cycles
• Toenails: 3–4 cycles

Continuous therapy (off-label for fingernails)

Itraconazole (100 mg) 1×2 po pc

• Fingernails: 6 weeks
• Toenails: 12 weeks

(Equivalent to Itraconazole 200 mg 1×1 po pc)

C. Fluconazole (Alternative, off-label)

Fluconazole (150–300 mg) 1×1 weekly po

• Fingernails: 3–6 months
• Toenails: longer duration required

Indication:

• Candida infection
• When terbinafine cannot be used

3. Topical Therapy (Only Mild Disease)

Indications:

• <50% nail involvement
• No nail matrix involvement

Options:

• Efinaconazole 10% solution daily × 48 weeks
• Ciclopirox 8% lacquer daily × 48 weeks
• Tavaborole 5% daily

Limitation: Lower efficacy, especially for toenails

4. Adjunctive Measures

• Nail debridement to improve drug penetration
• Treat concomitant tinea pedis/manuum
  • Terbinafine cream (1%) 1×1 topical for 2–4 weeks
• Keep nails dry
• Avoid occlusive footwear and trauma

5. Prevention

• Do not share nail instruments
• Keep feet dry
• Use antifungal powder if recurrent
• Treat close contacts if fungal infection present

---

3. High-Yield Table: Nail Psoriasis vs Onychomycosis

---

Exam Pearls

1. Pitting + oil-drop → Psoriasis
2. Confirm fungus before systemic antifungals
3. Terbinafine = best for fungal infection
4. Biologics = best for severe nail psoriasis
5. Psoriasis may mimic fungus → always rule out with KOH/PAS
6. Onycholysis with erythematous border → Psoriasis
7. Fungal debris is yellow-brown; psoriatic debris is white-chalky