A patient presents with the skin lesions shown in the image above. The lesions are erythematous, annular, and scaly with central clearing. What is the most likely diagnosis?

Explanation

## Image Findings * Multiple, well-demarcated, erythematous (red) lesions. * Annular (ring-shaped) morphology with some lesions coalescing. * Prominent raised, scaly borders. * Evidence of central clearing in several lesions. * Lesions are distributed over the trunk (abdomen and lower chest). ## Diagnosis **Key Point:** The classic presentation of erythematous, annular lesions with raised, scaly borders and central clearing is pathognomonic for **Tinea corporis**. Tinea corporis, commonly known as ringworm of the body, is a superficial dermatophyte infection of the trunk, extremities, or face. It is characterized by its typical annular shape, often with an active, erythematous, and scaly border that expands centrifugally, while the center tends to clear. This 'ringworm' appearance is highly suggestive of the diagnosis. ## Differential Diagnosis | Feature | Tinea Corporis | Psoriasis (Annular) | Urticaria | Granuloma Annulare | | :------------------ | :------------------------------------------- | :------------------------------------------------ | :---------------------------------------------- | :------------------------------------------------ | | **Morphology** | Annular, erythematous, scaly, central clearing | Annular plaques, silvery scales, less central clearing | Transient, edematous wheals, migratory | Annular papules/nodules, skin-colored/erythematous, no scale | | **Scales** | Prominent, especially at border | Silvery, thick, diffuse | Absent | Absent | | **Pruritus** | Common | Variable | Intense | Mild/absent | | **Duration** | Chronic, progressive | Chronic, relapsing | Transient (<24h per lesion) | Chronic | | **Pathology** | Fungal hyphae in stratum corneum | Epidermal hyperplasia, parakeratosis | Dermal edema, mast cell degranulation | Dermal granulomas | ## Clinical Relevance **Clinical Pearl:** Tinea corporis is often acquired through direct contact with infected humans, animals (especially pets like cats and dogs), or contaminated fomites. It's more common in warm, humid climates and among individuals with compromised immunity. ## High-Yield for NEET PG **High-Yield:** The **'active border'** (raised, erythematous, scaly edge) with **central clearing** is the most characteristic clinical feature distinguishing tinea corporis from other annular dermatoses. **Key Point:** Diagnosis is typically clinical, but can be confirmed by **KOH mount** of skin scrapings showing fungal hyphae. ## Common Traps **Warning:** Do not confuse the central clearing of tinea corporis with the uniform scaling of conditions like annular psoriasis. Also, remember that urticaria is transient and non-scaly, while granuloma annulare lacks scaling. ## Reference [cite:Bolognia, Dermatology, 4th ed., Ch 74; Harrison's Principles of Internal Medicine, 21st ed., Ch 149]