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BASICS

DESCRIPTION

  • Tinea cruris: infection of crural fold and gluteal cleft
  • Tinea corporis: infection involving face, trunk, and/or extremities; often presents with ring-shaped lesions (misnomer: ringworm)
  • Tinea capitis: infection of scalp and hair; may present with black dots from broken hairs Dermatophytes subsist on keratin, affecting skin, nails, and hair. Infection spread via contact with infected persons/animals:
  • Zoophilic: acquired from animals
  • Anthropophilic: acquired via personal contact (e.g., wrestling) or fomites
  • Geophilic: acquired from soil Synonyms: jock itch, ringworm

EPIDEMIOLOGY

Incidence

  • Tinea cruris: Any age; rare in children. Male > Female
  • Tinea corporis: Postpubertal children and young adults. Male = Female
  • Tinea capitis: Common in 3–9 years. Male = Female

Prevalence

  • Common worldwide with increasing incidence due to travel, socioeconomic factors, and animal contact

Pediatric Considerations

  • Tinea cruris rare before puberty
  • Tinea capitis common in children

Geriatric Considerations

  • Tinea cruris more frequent due to higher risk factors

Pregnancy Considerations

  • Tinea cruris and capitis are rare in pregnancy

ETIOLOGY AND PATHOPHYSIOLOGY

Causative Agents

  • Tinea cruris: Commonly Trichophyton rubrum, rarely Epidermophyton; often from patient’s tinea pedis
  • Tinea corporis: T. rubrum, T. tonsurans, Microsporum canis, T. interdigitale, M. gypseum, T. violaceum, M. audouinii, E. floccosum
  • Tinea capitis: T. tonsurans (90%), Microsporum spp. (10%) Genetic Susceptibility: Present in some individuals

RISK FACTORS

  • Warm climates, copious sweating
  • Daycare, schools
  • Immunosuppression (e.g., atopy, AIDS)
  • Obesity (cruris, corporis)
  • Animal contact (tinea corporis)

PREVENTION

  • Avoid contact with suspicious lesions
  • Fluconazole/itraconazole prophylaxis in wrestlers

COMMONLY ASSOCIATED CONDITIONS

  • Tinea pedis, tinea barbae, tinea manus

DIAGNOSIS

History

  • Symptoms: Asymptomatic to pruritic
  • Prior topical steroids may worsen presentation

Physical Exam

  • Tinea cruris: Well-marginated, erythematous, half-moon-shaped plaques, bilateral, sparing scrotum; may spread to buttocks/perianal region
  • Tinea corporis: Scaling, pruritic plaques, peripheral activity and central clearing, may have papules, pustules
  • Tinea capitis: Scaling patches, black-dot hairs, possible alopecia, may become pustular/nodular in late stages

Differential Diagnosis

  • Tinea cruris: Intertrigo, erythrasma, seborrheic dermatitis, psoriasis, candidiasis, acanthosis nigricans
  • Tinea capitis: Psoriasis, seborrheic dermatitis, pyoderma, alopecia areata, trichotillomania
  • Tinea corporis: Pityriasis rosea, eczema, dermatitis, syphilis, psoriasis, lupus, erythemas, granuloma annulare

Tests

  • Wood lamp: No fluorescence in T. rubrum
  • KOH prep: Branching hyphae from active border
  • Fungal culture: Sabouraud dextrose agar
  • Hair shaft: Arthrospores seen in capitis

TREATMENT

General Measures

  • Hand hygiene, launder clothing, avoid sharing towels/headgear, avoid tight clothing, avoid sports until treated
  • Evaluate close contacts and pets
  • For tinea capitis, antifungal shampoo for household
  • Avoid nystatin, use non-steroid anti-itch agents

First-Line Medication

  • Tinea cruris/corporis:
    • Topical terbinafine (1–3 weeks)
    • Econazole, ketoconazole BID x 2–3 weeks
    • Butenafine, continue 1 week after resolution
  • Tinea capitis:
    • PO griseofulvin (10–20 mg/kg/day for 6–12 weeks)
    • PO terbinafine: Weight-based dosing for 4–6 weeks
    • PO itraconazole: 100 mg/day for 6 weeks (>2 yrs)

Second-Line

  • For resistant or extensive disease or immunocompromised:
    • PO terbinafine, itraconazole
    • Fluconazole: 200 mg/week x 4 weeks Note: Monitor for liver toxicity, and check for drug interactions

REFERRAL

  • Nonresponsive or recurrent infections especially in immunocompromised

ADDITIONAL THERAPIES

  • Treat secondary bacterial infections

FOLLOW-UP

  • Monitor LFTs during oral antifungal therapy
  • Reevaluate treatment response

PATIENT EDUCATION

  • Discuss causative agents, risk factors, and prevention

PROGNOSIS

  • Excellent with treatment
  • Tinea capitis may resolve in 6 months, but scarring possible

COMPLICATIONS

  • Secondary bacterial infection
  • Dermatophytid reactions
  • Invasive dermatophyte infection

CODES - ICD10

  • B35.0 – Tinea barbae and capitis
  • B35.4 – Tinea corporis
  • B35.6 – Tinea cruris

CLINICAL PEARLS

  • Tinea corporis: Scaly plaque, peripheral activity, central clearing
  • Tinea cruris: Erythematous plaque in folds, sparing scrotum
  • Treat concomitant tinea pedis
  • Tinea capitis: fungal scalp infection with possible black dots