Kerion (Inflammatory Tinea Capitis)
A kerion is a severe, intensely inflammatory form of tinea capitis (dermatophyte fungal infection of the scalp). It represents a robust host cell-mediated immune response to the fungal pathogen.
Key Clinical Features
- Appearance: A boggy, tender, fluctuant, indurated plaque on the scalp.
- Associated Signs: Often accompanied by alopecia (hair loss), crusting, and post-auricular or cervical lymphadenopathy.
- Misdiagnosis: Frequently mistaken for a bacterial abscess; however, incision and drainage (I&D) are contraindicated as it will not yield pus and may exacerbate inflammation.
Diagnostic & Management Pearls
| Aspect | Details |
|---|---|
| Diagnosis | Fungal culture of hair/scales or KOH preparation showing fungal elements. |
| Treatment | Requires systemic oral antifungals (e.g., Griseofulvin, Terbinafine) for extended periods. |
High-Yield Exam Pearl:
- Anti-inflammatory steroids: While the lesion is inflammatory, systemic steroids are generally reserved for cases where there is a high risk of permanent cicatricial (scarring) alopecia.
- Pathogens: Most commonly caused by zoophilic dermatophytes, particularly Microsporum canis or Trichophyton tonsurans.