A 35-year-old male farmer presents with a 3-month history of a well-demarcated, scaly, erythematous patch on the dorsum of his left hand with central clearing and raised borders. Fungal culture confirms Trichophyton mentagrophytes. What is the drug of choice for tinea corporis in this patient?

## Drug of Choice for Tinea Corporis **Key Point:** For tinea corporis (body ringworm), the choice of antifungal depends on extent and duration. Topical agents are first-line for localized disease; systemic therapy is reserved for extensive, recurrent, or immunocompromised cases. ### Clinical Assessment of This Case - **Duration:** 3 months (chronic/persistent) - **Site:** Dorsum of hand (exposed, occupational exposure in farmer) - **Organism:** *Trichophyton mentagrophytes* (anthropophilic; common in tinea corporis) - **Morphology:** Well-demarcated, central clearing, raised borders (classic "ringworm" appearance) **High-Yield:** While topical azoles are first-line for **acute, localized** tinea corporis, this patient has a **3-month history** with occupational exposure (farmer), suggesting either: 1. Failure of topical therapy, or 2. Risk of recurrence due to occupational re-exposure In such cases, **systemic terbinafine** is preferred because it: - Penetrates all skin layers and hair follicles - Prevents relapse in occupational settings - Achieves faster cure (2–4 weeks vs. 3–4 weeks topical) - Is fungicidal ### Treatment Algorithm for Tinea Corporis ```mermaid flowchart TD A["Tinea corporis diagnosed"]:::outcome --> B{"Extent & Duration?"}:::decision B -->|"Acute, localized<br/><2 weeks"| C["Topical azole<br/>or terbinafine cream"]:::action B -->|"Chronic >3 weeks<br/>or extensive"| D["Systemic terbinafine<br/>250 mg OD × 2-4 weeks"]:::action B -->|"Immunocompromised<br/>or recurrent"| E["Systemic terbinafine<br/>or itraconazole"]:::action C --> F["Review at 3-4 weeks"]:::action D --> G["Cure expected in<br/>2-4 weeks"]:::outcome E --> H["Monitor for relapse"]:::action ``` ### Comparison of Antifungals for Tinea Corporis | Agent | Route | Dose | Duration | Best For | Notes | |-------|-------|------|----------|----------|-------| | **Terbinafine** | Oral | 250 mg OD | 2–4 weeks | **Chronic/extensive**; fungicidal | Preferred systemic agent | | Clotrimazole | Topical | 1% cream BD | 2–3 weeks | Acute, localized | First-line topical | | Griseofulvin | Oral | 500 mg BD | 6–12 weeks | Older standard | Fungistatic; slower; rarely used now | | Itraconazole | Oral | 100 mg OD | 4 weeks | Alternative; pulse dosing available | Less preferred than terbinafine | **Clinical Pearl:** The **3-month duration** is the key clinical clue. Acute tinea corporis (< 2 weeks) responds well to topical azoles. Chronic or recurrent disease (especially in occupational settings) requires systemic therapy to prevent relapse. ### Why Terbinafine Over Griseofulvin? 1. **Fungicidal vs. Fungistatic:** Terbinafine kills fungi; griseofulvin only stops growth 2. **Duration:** Terbinafine: 2–4 weeks; griseofulvin: 6–12 weeks 3. **Efficacy:** Terbinafine: >95% cure; griseofulvin: 70–80% 4. **Modern standard:** Terbinafine is now preferred in all major guidelines **Tip:** In NEET PG, if a tinea corporis question specifies **"chronic," "extensive," "recurrent," or "occupational exposure,"** the answer is almost always **systemic terbinafine**.