Dermatophytosis (Tinea)
Tinea infections are superficial fungal infections of the keratinized tissues (skin, hair, nails) caused by dermatophytes (*Trichophyton*, *Microsporum*, *Epidermophyton*).
Common Clinical Presentations
| Condition | Key Features |
|---|---|
| Tinea Corporis | “Ringworm”; annular plaques with central clearing and active, scaly borders. |
| Tinea Capitis | Scalp scaling, “black dot” alopecia, can lead to an inflammatory Kerion. |
| Tinea Pedis | “Athlete’s foot”; interdigital maceration or hyperkeratotic “moccasin” distribution. |
| Tinea Unguium | Onychomycosis; nail thickening, subungual debris, and discoloration. |
Diagnostic & Management Pearls
- KOH Preparation: The diagnostic gold standard. Visualize branching, septate hyphae in skin scrapings or nail clippings.
- Treatment:
- Localized skin lesions: Topical allylamines (e.g., Terbinafine) or azoles (e.g., Clotrimazole).
- Systemic therapy: Mandatory for Tinea Capitis and Tinea Unguium. Oral Terbinafine is often the first-line choice.
High-Yield Exam Pearl:
- Tinea Incognito: The result of applying potent topical steroids to a fungal infection. The rash loses its classic annular/scaly border, becomes more diffuse, and may look like eczema, but it continues to expand.
- Wood’s Lamp: Useful for specific types of Tinea Capitis (e.g., *Microsporum* species fluoresce blue-green), though it is less sensitive for *Trichophyton* species.