Tinea Infections (corporis, capitis, pedis, cruris, versicolor)

Symptoms

• Pruritus (mild to moderate)
• Scalp scaling, hair loss (capitis)
• Burning, fissuring between toes (pedis)
• Cosmetic concerns (versicolor)

Signs / physical exam

• Tinea corporis: annular erythematous plaque with raised scaly active border and central clearing; satellite lesions if extensive
• Tinea capitis: scaly patches with broken hairs ('black dot' pattern from endothrix T. tonsurans); kerion = boggy inflammatory mass with pustules and lymphadenopathy; favus = yellow scutula crusts
• Tinea pedis: interdigital maceration and fissuring (most common); moccasin pattern (chronic hyperkeratosis covering plantar/lateral foot); vesiculobullous (acute inflammatory)
• Tinea cruris: erythematous scaly plaques in inguinal folds extending to medial thighs, SCROTUM SPARED (vs candida — scrotum involved)
• Tinea manuum: 'two feet-one hand' syndrome — dry hyperkeratotic palm
• Onychomycosis: yellow/white nail discoloration, subungual hyperkeratosis, onycholysis, dystrophy (distal subungual most common)
• Tinea versicolor: hypo- or hyperpigmented finely scaling macules and patches on upper trunk, neck, shoulders; 'fawn-colored' or pink in untanned skin

Classic findings

Active raised scaly border with central clearing (corporis); KOH 'spaghetti and meatballs' (versicolor); Wood's lamp yellow-green fluorescence (Microsporum tinea capitis).

Diagnostic criteria

KOH and/or culture positivity in characteristic clinical setting.

Labs

• KOH preparation of scale or hair: branching septate hyphae (dermatophyte) or short hyphae + spores ('spaghetti and meatballs') for versicolor
• Fungal culture (Sabouraud or DTM agar) — confirms species, especially for capitis and onychomycosis before systemic therapy
• Wood's lamp: blue-green fluorescence with Microsporum tinea capitis (T. tonsurans is non-fluorescent); pale yellow with versicolor; coral-red with erythrasma
• PAS-stained nail clipping or PCR for onychomycosis diagnosis
• Baseline LFTs before oral terbinafine or itraconazole

Imaging

• Not indicated

First-line

• Tinea corporis / cruris / pedis (limited): topical antifungal — clotrimazole 1% BID, ketoconazole 2% BID, terbinafine 1% BID, ciclopirox 0.77% BID — continue 1-2 weeks beyond clinical resolution (typically 2-4 weeks)
• Tinea pedis (moccasin or extensive): oral terbinafine 250 mg daily × 2 weeks OR oral itraconazole 200 mg BID × 1 week pulse
• Tinea capitis (REQUIRES SYSTEMIC): oral griseofulvin (microsize) 20-25 mg/kg/day × 6-8 weeks (preferred for Microsporum) OR oral terbinafine 3-6 mg/kg/day × 4-6 weeks (preferred for Trichophyton tonsurans, more common in US); adjunctive selenium sulfide or ketoconazole shampoo 2-3x/wk reduces shedding and transmission
• Onychomycosis: oral terbinafine 250 mg daily × 6 weeks (fingernails) or 12 weeks (toenails) — most effective; alternatives: itraconazole pulse, fluconazole weekly; topical efinaconazole or tavaborole if oral contraindicated
• Tinea versicolor: topical selenium sulfide 2.5% lotion, ketoconazole 2% shampoo, or clotrimazole — lather, leave 10 min, rinse — daily × 1-2 weeks; or oral itraconazole 200 mg/day × 5-7 days for widespread/refractory (avoid oral fluconazole single-dose regimens that were once popular — relapse common)

Kerion (inflammatory tinea capitis)

• Oral antifungal (terbinafine or griseofulvin) PLUS short course oral prednisone 0.5-1 mg/kg/day × 5-10 days to reduce scarring alopecia
• Antibiotic only if bacterial superinfection — DO NOT drain kerion (sterile inflammation)

Tinea incognito (steroid-modified)

• Discontinue topical corticosteroid
• Treat with appropriate antifungal — often requires systemic therapy because of extensive subclinical spread

Second-line / adjunct

• Avoid systemic ketoconazole due to hepatotoxicity and adrenal suppression risk (FDA boxed warning)
• Recheck culture and consider drug resistance (e.g., Trichophyton indotineae — emerging terbinafine-resistant species)
• Counsel on hygiene: clean and dry skin folds, antifungal foot powder, change socks, treat shoes with antifungal spray