Arm, truk fungal infection which is treatment

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Fungal Infection of the Arm & Trunk (Tinea Corporis)

Tinea corporis ("ringworm") is a dermatophyte infection of the glabrous (relatively hairless) skin of the body — commonly the arms, trunk, legs, and face. The causative organisms are Trichophyton rubrum (most common), T. interdigitale, Microsporum canis, and Epidermophyton floccosum.

Tinea corporis — annular, scaly, erythematous plaque with raised border on the arm

Tinea corporis: circular erythematous plaque with raised, scaly border — classic "ringworm" appearance

Clinical Features

Erythematous, scaly plaques with an annular (ring-shaped) appearance
Active, raised, scaly border with central clearing
Itchy (pruritic)
Deep inflammatory nodules/granulomas can occur if inappropriately treated with topical corticosteroids

Diagnosis

KOH preparation of skin scrapings: reveals fungal hyphae
Culture or histology (PAS stain) if needed

Treatment

1. Topical Antifungals — First Line for Mild/Limited Disease

Apply twice daily for 2–4 weeks (continue 1 week beyond clinical resolution):

Drug Class	Examples
Allylamines	Terbinafine 1% cream/gel (most effective; can be once daily × 7 days)
Imidazoles	Clotrimazole 1%, Miconazole 2%, Ketoconazole 2% cream
Other	Tolnaftate, Butenafine, Ciclopirox

Terbinafine 1% cream once daily for 7 days is highly effective for tinea corporis. — Textbook of Family Medicine 9e

2. Oral Antifungals — For Widespread, Inflammatory, or Recalcitrant Disease

Drug	Dose	Notes
Terbinafine	250 mg once daily × 2–4 weeks	Most effective oral agent; fungicidal
Itraconazole	100–200 mg/day	Check for drug interactions (CYP450); avoid in heart failure
Griseofulvin	500 mg/day (microsize)	Older agent; approved for skin/hair/nail dermatophytosis; SE: GI upset, headache
Fluconazole	150 mg once weekly	Alternative option

Oral antifungal agents are reserved for widespread or more inflammatory eruptions. — Fitzpatrick's Dermatology

All oral agents may cause hepatotoxicity. Should not be used in pregnant or breastfeeding women. — Harrison's Principles of Internal Medicine 22E

Special Situations

Situation	Management
Tinea incognito (steroid-modified tinea)	Stop corticosteroid; treat with topical/oral antifungal
Extensive/recurrent disease	Oral terbinafine or itraconazole
Immunocompromised host	Oral therapy preferred; longer duration
Follicular involvement (Majocchi granuloma)	Oral antifungals required (topicals ineffective)

Key Points

Do NOT use topical corticosteroids alone — worsens infection and causes tinea incognito
Nystatin is not active against dermatophytes (only useful for Candida)
Keep skin dry and clean — fungal infections thrive in moisture
Treat close contacts and shared fomites (towels, clothing) to prevent reinfection

Sources: Harrison's Principles of Internal Medicine 22E, Fitzpatrick's Dermatology, Goldman-Cecil Medicine, Textbook of Family Medicine 9e

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