Tinea Infections (corporis, capitis, pedis, cruris, versicolor)
Superficial dermatophyte (and Malassezia) infections of skin, hair, and nails with site-specific presentations.
Also known as: tinea, ringworm, dermatophytosis, athlete's foot, jock itch, tinea versicolor, pityriasis versicolor
Overview
Superficial fungal infections of keratinized tissue. Dermatophyte tineas (Trichophyton, Microsporum, Epidermophyton) cause classic ringworm of body (corporis), scalp (capitis), feet (pedis), groin (cruris), hands (manuum), and nails (unguium/onychomycosis). Tinea versicolor (pityriasis versicolor) is caused by Malassezia furfur — a yeast, not a true dermatophyte.
Epidemiology
Tinea pedis is the most common dermatophytosis worldwide (~10% point prevalence). Tinea capitis predominantly affects prepubertal children, especially Black children in the US (Trichophyton tonsurans). Tinea versicolor is common in adolescents and young adults in humid climates.
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Risk factors
- Warm humid climates, occlusive footwear, sweating
- Communal showers, gyms, pools, wrestling/martial arts ('tinea gladiatorum')
- Diabetes mellitus, obesity, immunosuppression
- Topical corticosteroid use (tinea incognito — masked inflammation, spreading edge)
- Animal exposure (Microsporum canis — kittens, puppies; zoonotic kerion)
- Family member with tinea capitis (shared combs, hats)
Pathophysiology
Dermatophytes secrete keratinases that allow invasion of stratum corneum, hair, and nail. Inflammation results from host immune response; minimal inflammation in immunosuppressed → 'tinea incognito' under steroids. Malassezia is a lipophilic yeast colonizing sebaceous skin; conversion from yeast to mycelial form produces clinical pityriasis versicolor; azelaic acid produced by the organism inhibits melanocytes (hypopigmentation).
Clinical presentation
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).
Differential diagnosis
- Nummular eczema — Coin-shaped, no central clearing, KOH negative
- Psoriasis — Silvery scale, extensor surfaces, nail pitting
- Seborrheic dermatitis — Greasy scale in seborrheic distribution
- Pityriasis rosea — Herald patch + Christmas-tree truncal eruption
- Erythrasma (groin/folds) — Coral-red Wood's lamp fluorescence (Corynebacterium minutissimum); thin brown patches; treat with erythromycin/clindamycin
- Granuloma annulare — Smooth annular skin-colored to violaceous papules without scale; KOH negative
- Alopecia areata (vs tinea capitis) — Smooth bald patches without scale, exclamation point hairs, no broken hairs at scalp; KOH/culture negative
- Vitiligo (vs tinea versicolor) — Complete depigmentation, no scale, Wood's lamp bright milky white fluorescence
Diagnostic workup
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
Diagnostic algorithm
| Variant | Site / Lesion | Preferred Therapy |
|---|---|---|
| Corporis (ringworm) | Annular plaque, raised scaly border, central clearing | Topical azole or terbinafine 2-4 wks |
| Capitis | Scaly scalp, broken hairs, ± kerion | Oral terbinafine or griseofulvin × 4-8 wks + antifungal shampoo |
| Pedis | Interdigital maceration; moccasin hyperkeratosis | Topical terbinafine; oral if moccasin/extensive |
| Cruris | Inguinal scaly plaques sparing scrotum | Topical azole or terbinafine |
| Onychomycosis | Yellow nail, subungual debris, onycholysis | Oral terbinafine 6 wks (fingers) / 12 wks (toes) |
| Versicolor | Hypo/hyperpigmented finely scaling macules on trunk | Selenium sulfide or ketoconazole shampoo; oral itraconazole if extensive |
Treatment
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
Complications
- Scarring alopecia from untreated kerion
- Bacterial superinfection (impetigo, cellulitis), especially with maceration
- Onychomycosis: chronic relapsing course, gateway for cellulitis in diabetics
- Id reaction (autoeczematization): vesicular dermatitis on hands during active tinea pedis — sterile, immune-mediated
- Terbinafine adverse effects: hepatotoxicity, taste disturbance, drug interactions (CYP2D6)
- Itraconazole adverse effects: heart failure exacerbation, drug interactions (potent CYP3A4 inhibitor)
PANCE pearls
- Tinea cruris spares the scrotum; candida intertrigo involves the scrotum with satellite pustules — quick distinguishing feature.
- Pruritic annular plaque with central clearing and active border = tinea corporis until proven otherwise — KOH first, treat empirically only if KOH unavailable.
- NEVER use topical betamethasone/clotrimazole combination (Lotrisone) — the steroid potency is too high for the skin folds where it is commonly used; causes atrophy and tinea incognito.
- Tinea capitis is the only superficial fungal infection that REQUIRES systemic therapy — topicals will not penetrate hair shaft.
- Tinea versicolor responds to therapy but pigment changes can take months to fade — counsel patients to avoid attributing relapse to treatment failure.
References
- AAD 2014 — Guidelines of Care for Superficial Mycotic Infections of the Skin: Tinea Corporis, Tinea Cruris, Tinea Pedis (Drake et al.; updated standards)
- Cochrane 2016 — Systemic Antifungal Therapy for Tinea Capitis in Children (Chen et al., Cochrane Database Syst Rev 2016)
- AAFP 2014 — Diagnosis and Management of Tinea Infections (Ely, Rosenfeld, Stone, Am Fam Physician 2014)
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