Diagnosis (Lesion Characteristics)

🟢 Tinea corporis (ringworm of body)

• Annular (“ring-shaped”) lesion with erythematous, scaly, raised border and central clearing.
• Usually on trunk, arms, or legs.
• Often pruritic.

🟢 Tinea cruris (jock itch)

• Well-demarcated erythematous plaques with scaly, raised margins in the inguinal folds.
• Typically spares the scrotum (unlike candidiasis).
• May extend to the upper thigh or buttock.

🟢 Tinea pedis (athlete’s foot)

• Interdigital type: maceration, fissures, and scaling between toes (esp. 3rd–4th).
• Moccasin type: diffuse dry scaling on soles/lateral feet (“slipper-like” pattern).
• Vesicular type: vesicles/blisters on the medial foot or sole.
• Often associated with itching, burning, or odor.

🟣 Tinea capitis (scalp ringworm)

• Patchy alopecia with scaling and broken hairs (“black dot” pattern).
• Posterior cervical lymphadenopathy is common.
• Kerion: boggy, tender inflammatory mass with pustules → risk scarring alopecia.
• Favus: yellow cup-shaped crusts (scutula), foul odor.
• May fluoresce under Wood’s lamp (Microsporum).

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Laboratory confirmation (for all sites)

• KOH preparation → reveals septate, branching hyphae.
• Fungal culture (Sabouraud agar) → identifies species (e.g., Trichophyton, Microsporum).
• Wood’s lamp → useful in tinea capitis, shows green fluorescence in Microsporum species.

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💊 Management of Dermatophytosis by Site

🟢 Tinea corporis (body ringworm)

General

• Keep skin dry, avoid tight clothing.
• Treat household contacts if recurrent.

Definitive Treatment

• Topical antifungals (first-line, localized)
  • Clotrimazole 1% cream bid × 2–4 weeks.
  • Miconazole 2% cream bid × 2–4 weeks.
  • Ketoconazole 2% cream od–bid × 2–4 weeks.
  • Terbinafine 1% cream od × 1–2 weeks.
• Systemic antifungals (extensive / resistant / immunocompromised)
  • Terbinafine 250 mg po qd × 2 weeks.
  • Itraconazole 100 mg po bid × 2 weeks (or 200 mg qd × 1 week).
  • Fluconazole 150 mg po once weekly × 2–4 weeks.

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🟢 Tinea cruris (jock itch)

General

• Loose cotton underwear, weight reduction if obese.
• Keep groin dry; use antifungal powder if needed.

Definitive Treatment

• Topical antifungals (first-line, localized)
  • Clotrimazole 1% cream bid × 2–4 weeks.
  • Miconazole 2% cream bid × 2–4 weeks.
  • Ketoconazole 2% cream od–bid × 2–4 weeks.
  • Terbinafine 1% cream od × 1–2 weeks.
• Systemic antifungals (for recurrent / resistant cases)
  • Terbinafine 250 mg po qd × 2 weeks.
  • Itraconazole 100 mg po bid × 2 weeks.
  • Fluconazole 150 mg po once weekly × 2–4 weeks.

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🟢 Tinea pedis (athlete’s foot)

General

• Keep feet dry, change socks frequently, avoid occlusive shoes.
• Antifungal powders in footwear.

Definitive Treatment

• Topical antifungals (first-line, localized)
  • Clotrimazole 1% cream bid × 4 weeks.
  • Miconazole 2% cream bid × 4 weeks.
  • Ketoconazole 2% cream od–bid × 4 weeks.
  • Terbinafine 1% cream od × 2–4 weeks.
• Systemic antifungals (chronic moccasin-type, recurrent, resistant)
  • Terbinafine 250 mg po qd × 4–6 weeks.
  • Itraconazole 100 mg po bid × 2 weeks.
  • Fluconazole 150 mg po once weekly × 4–6 weeks.

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🟣 Tinea capitis (scalp ringworm)

⚠️ Topicals alone do not cure — systemic antifungal is required.

General

• Selenium sulfide 1–2.5% shampoo or ketoconazole 2% shampoo, 2–3×/week for 2–4 weeks (adjunct, reduce transmission).
• Screen/treat close contacts.

Definitive Treatment (systemic mandatory)

• Griseofulvin (micronized) (20–25 mg/kg/day) po with fatty meal × 6–8 weeks
  • First-line, especially if Microsporum is suspected.
• Terbinafine (weight-based) po × 4–6 weeks
  • <20 kg: 62.5 mg qd
  • 20–40 kg: 125 mg qd
  • 40 kg: 250 mg qd
  • More effective for Trichophyton (the most common cause).
• Alternatives
  • Itraconazole 3–5 mg/kg/day po × 4–6 weeks, or pulse 5 mg/kg/day × 1 week on/2 off × 2–3 pulses.
  • Fluconazole 6 mg/kg/day po × 3–6 weeks, or 12 mg/kg once weekly × 6 weeks.
• Kerion (inflammatory type)
  • Add prednisone ~1 mg/kg/day × 5–7 days to reduce inflammation & prevent scarring alopecia.

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⚠️ Key Exam Pearls

• Corporis: annular lesion with central clearing → topical therapy usually enough.
• Cruris: groin, spares scrotum → topical terbinafine 1% od × 1–2 weeks first-line.
• Pedis: interdigital vs moccasin type → may need systemic terbinafine 4–6 weeks.
• Capitis: must use systemic antifungal (griseofulvin/terbinafine) → topicals only adjunct.
• Steroid creams ❌ contraindicated → cause tinea incognito.