Diagnostic approach to tinea capitis with kerion: A retrospective study

Area of Science:

• Dermatology
• Mycology
• Pediatrics

Background:

• Kerion is an inflammatory tinea capitis presenting as boggy, crusted nodules.
• Accurate diagnosis of kerion is often hindered by frequent false-negative results from mycological samples.

Purpose of the Study:

• To evaluate the rates of false-negative mycological samples in children diagnosed with kerion before initiating antifungal therapy.
• To assess the impact of pre-treatment with oral antibiotics and/or steroids on diagnostic yield.

Main Methods:

• A retrospective study analyzed mycological samples (direct microscopy and fungal culture) from 23 children with kerion.
• Specimens were collected at baseline and after a course of oral antibiotics with or without oral steroids.
• Kerion inflammation was categorized as highly inflammatory (painful, moist, purulent discharge, or exuberant crust) or mildly inflammatory (erythematous, dry).

Main Results:

• Highly inflammatory kerions showed significantly higher rates of culture negativity at baseline (80%) compared to mildly inflammatory kerions (16.7%).
• Following antibiotic and steroid treatment, positive fungal culture rates for highly inflammatory kerions increased significantly (90.9%).
• Non-inflammatory tinea capitis lesions, when present, were culture-positive in all cases.

Conclusions:

• High rates of negative fungal cultures are primarily associated with highly inflammatory kerion.
• Administering oral antibiotics and steroids before sampling can improve the diagnostic yield for highly inflammatory kerion.
• Sampling concurrent non-inflammatory tinea capitis lesions offers the highest sensitivity for fungal detection.