Tinea Unguium

Tinea unguium is dermatophyte infection of the nail plate, mostly Trichophyton rubrum, T. mentagrophytes and Epidermophyton floccosum. It makes up about half of all nail dystrophy and is more common in toenails.

• Risk factors: older age, tinea pedis, diabetes, peripheral vascular disease, HIV, immunosuppression, trauma, communal showers, occlusive footwear, family history.
• A reservoir for recurrent tinea pedis and for spread to others.

Nail thickening, discolouration (white, yellow or brown), subungual debris, onycholysis and crumbling, most often distal and lateral subungual, or white superficial and proximal subungual in immunosuppression.

• Usually painless; pain with pressure or thickened nails in the elderly.
• Differential diagnosis: nail psoriasis, lichen planus, candidal onychomycosis, traumatic onychodystrophy, yellow nail syndrome, subungual melanoma, bacterial infection (Pseudomonas green discolouration), chronic paronychia, contact dermatitis.
• Complications: pain, secondary bacterial infection, cellulitis in diabetes, ulceration in neuropathic feet, psychosocial distress, recurrence, spread to other nails.

Confirm before prolonged oral therapy.

• Nail clippings and subungual scrapings for KOH microscopy, fungal culture and PAS stained histology or PCR.
• Baseline liver function tests, full blood count, glucose, HIV test where risk.
• Dermoscopy and biopsy for single pigmented streak.

Oral therapy is most effective; topical therapy suits mild disease, contraindication to oral drugs, or adjunct.

• Supportive: keep feet dry, cotton socks, treat tinea pedis, trim and file nails, disinfect shoes, avoid trauma and barefoot walking in communal areas, foot care for diabetes.
• Pharmacological: terbinafine 250 mg daily for 6 weeks for fingernails and 12 weeks for toenails (children by weight: under 20 kg 62.5 mg, 20 to 40 kg 125 mg, over 40 kg 250 mg). Alternatives: itraconazole 200 mg daily for 12 weeks or pulse 400 mg daily for one week per month (2 pulses for fingernails, 3 pulses for toenails); fluconazole 150 to 450 mg once weekly until the nail grows out (about 6 months for fingernails and 9 to 12 months for toenails). Topical amorolfine 5 percent lacquer once or twice weekly for 6 to 12 months, or ciclopirox 8 percent lacquer daily, for superficial or limited distal disease (up to 50 percent involvement without matrix involvement).
• Procedures: mechanical or chemical debridement (urea 40 percent paste), nail avulsion for painful severe nails, laser therapy where available.
• Special groups: pregnancy, avoid oral drugs and use topical lacquer or defer; liver disease, avoid terbinafine and itraconazole; heart failure, avoid itraconazole; drug interactions with itraconazole (statins, warfarin, calcium channel blockers) and terbinafine (tricyclics, beta blockers); diabetes and vascular disease, regular foot care and podiatry.
• Red flags: single pigmented band (melanoma), pain with swelling, spreading cellulitis, jaundice or dark urine on therapy, systemic fever.
• Follow-up: check liver tests at 4 to 6 weeks if therapy exceeds 6 weeks; review at 3 to 6 months; note that clear nail takes 12 to 18 months to grow out for toenails.