What is the recommended treatment for a patient presenting with Kerion?

Treatment of Kerion

The recommended first-line treatment for kerion is oral antifungal therapy with either griseofulvin or terbinafine, with the choice guided by the causative dermatophyte species. 1

Diagnosis and Clinical Features

Kerion is a severe inflammatory reaction that occurs in some cases of fungal infection of the hair or hair follicles, presenting as an inflammatory mass with pustular and tender plaques on the scalp 2. It represents a massive delayed-type hypersensitivity reaction to a dermatophyte infection 3.

Before initiating treatment:

• Collect scalp lesion samples via scalpel scraping, hair pluck, brush, or swab
• Process specimens for microscopy and culture to identify the causative organism
• Begin treatment while awaiting confirmatory mycology when kerion is clinically suspected 1

Treatment Algorithm

First-line Therapy

1. Systemic Antifungal Therapy (choose based on causative organism):

   • For Trichophyton species infections:

     • Terbinafine (preferred due to shorter treatment course):
       • <20 kg: 62.5 mg daily for 2-4 weeks
       • 20-40 kg: 125 mg daily for 2-4 weeks

       • 40 kg: 250 mg daily for 2-4 weeks

   • For Microsporum species infections:

     • Griseofulvin:
       • <50 kg: 15-20 mg/kg/day (single or divided dose) for 6-8 weeks

       • 50 kg: 1 g/day (single or divided dose) for 6-8 weeks 1

2. Important note: Topical therapy alone is not recommended for kerion treatment. Oral therapy is generally indicated to achieve both clinical and mycological cure. 1

Adjunctive Therapy

• Anti-inflammatory treatment: While controversial, some evidence suggests targeting inflammation may be beneficial in kerion management 3
• Sporicidal shampoos (e.g., selenium sulfide) to remove adherent scales and hasten eradication of viable spores from the scalp 4

Second-line Therapy

If there is treatment failure (no clinical improvement):

• Itraconazole is effective against both Trichophyton and Microsporum species 1
• Consider switching from terbinafine to griseofulvin for Microsporum infections, or vice versa for Trichophyton infections 1

Treatment Considerations

• Duration of therapy: Continue first-line therapy for the recommended duration (2-4 weeks for terbinafine, 6-8 weeks for griseofulvin)
• Treatment failure: Consider lack of compliance, suboptimal absorption, relative insensitivity of the organism, or reinfection
• Clinical improvement but ongoing positive mycology: Continue current therapy for an additional 2-4 weeks 1

Evidence Analysis

The British Association of Dermatologists' guidelines provide the strongest evidence for kerion management 1. While some studies have investigated the use of oral corticosteroids as adjunctive therapy, a randomized trial comparing griseofulvin plus oral prednisolone versus griseofulvin alone showed no significant difference in cure rates at 12 weeks 5, suggesting that antifungal therapy alone may be sufficient.

Newer treatment approaches like photodynamic therapy (PDT) combined with antifungals have shown promise in case reports for resistant cases 2, but these should be considered only after standard therapies have failed.

Common Pitfalls and Caveats

• Avoid topical therapy alone as it is insufficient for treating kerion 1
• Do not delay systemic antifungal treatment while awaiting culture results when kerion is clinically suspected 1
• Be aware that terbinafine is less effective against Microsporum species infections and may require higher doses for longer periods in these cases 1
• Monitor for side effects of antifungal therapy, including gastrointestinal disturbances and rashes, though these are generally uncommon (<8% for terbinafine) 1