The clinical image of the foot shown above demonstrates erythematous, scaling, and vesicular lesions, some with erosions and crusting. Which of the following is the most likely diagnosis?

Explanation

## Image Findings * Erythematous patches and plaques on the dorsal aspect of the foot and toes. * Scaling, particularly visible on the toes and interdigital areas. * Multiple small vesicles and bullae, some ruptured, leading to erosions and crusting, especially on the dorsal foot. * Irregular, somewhat serpiginous borders of the lesions. ## Diagnosis **Key Point:** The presence of erythematous, scaling, and vesiculobullous lesions, particularly in the interdigital spaces and on the dorsal foot, is highly suggestive of **Tinea Pedis (Athlete's Foot)**. Tinea pedis is a common dermatophyte infection of the feet. The image displays features consistent with the **inflammatory or vesiculobullous type** of tinea pedis, characterized by pruritic vesicles, bullae, erythema, and scaling. These lesions often occur on the instep, sole, or dorsal aspect of the foot and can be accompanied by erosions and crusting from ruptured blisters. The distribution and morphology are classic for a fungal infection. ## Differential Diagnosis | Feature | Tinea Pedis (Vesiculobullous) | Contact Dermatitis | Dyshidrotic Eczema (Pompholyx) | Psoriasis (Pustular) | | :------------------ | :---------------------------------------------------------- | :----------------------------------------------------- | :----------------------------------------------------- | :----------------------------------------------------- | | **Lesion Morphology** | Erythema, scaling, vesicles, bullae, erosions, crusts, often unilateral | Erythema, vesicles, bullae, edema, well-demarcated | Deep-seated vesicles/bullae, pruritus, often bilateral, palms/soles | Erythema, scaling, pustules, often bilateral, well-demarcated plaques | | **Distribution** | Interdigital, plantar, dorsal foot; often unilateral | Area of contact with allergen | Palms, soles, lateral fingers/toes; often bilateral | Extensor surfaces, scalp, nails; can affect soles | | **Key Feature** | Fungal etiology (KOH positive), often pruritic | History of exposure, patch test positive | Recurrent, stress-related, non-infectious | Silvery scales, Auspitz sign, nail pitting | ## Clinical Relevance **Clinical Pearl:** Tinea pedis is often associated with hyperhidrosis, occlusive footwear, and communal wet environments. It is a common source of fungal infection for other body sites (e.g., tinea cruris, tinea manuum). ## High-Yield for NEET PG **High-Yield:** The **vesiculobullous type of tinea pedis** often presents with pruritic vesicles and bullae, especially on the instep or dorsal foot, and can be mistaken for dyshidrotic eczema or contact dermatitis. A **KOH mount** is crucial for diagnosis. **Key Point:** **Trichophyton rubrum** is the most common causative organism for tinea pedis. ## Common Traps **Warning:** Differentiating tinea pedis from dyshidrotic eczema or contact dermatitis solely based on morphology can be challenging. Always consider a **KOH examination** to confirm fungal etiology, especially in atypical presentations or when treatment fails. ## Reference [cite:Rohit, Kumar. (2020). Dermatology. Jaypee Brothers Medical Publishers. Ch 14, Fungal Infections of the Skin.]