Pediatrics · Year 3 · from Pediatrics
Case 2: Tinea Capitis with Kerion
Patient Demographics
- Age: 6-year-old male
- Sex: Male
Chief Complaint
"He has a big swollen bump on his head with hair falling out."
History of Present Illness
A 6-year-old boy is brought in by his mother with a 3-week history of a progressively enlarging scalp lesion. It began as a small scaly patch with some hair loss but has now become raised, boggy, and painful. Over the past week, the area has started draining pus, and there has been significant hair loss in the affected area. He has had low-grade fever for 2 days. Several of his classmates have had ringworm treated recently. The family has a new kitten at home. His mother tried antifungal cream without improvement.
Physical Examination
- Vital Signs: Temperature 38.1C, HR 92 bpm
- General: Alert, well-appearing boy
- Scalp:
- 5 cm boggy, indurated, tender nodule on the right parietal scalp
- Multiple pustules and draining sinuses on the surface
- Alopecia with broken hair shafts ("black dots") at the margins
- Surrounding area shows scaly, erythematous patches with hair loss
- Lymph nodes: Right posterior cervical lymphadenopathy (3 cm, tender)
- Skin: No tinea corporis lesions visible
Laboratory Findings
- KOH preparation (from hair shafts): Ectothrix pattern with spores surrounding hair shaft
- Fungal culture: Microsporum canis (pending final confirmation)
- Wood's lamp: Bright green fluorescence (characteristic of Microsporum species)
Diagnosis
Tinea capitis with kerion formation (Microsporum canis)
Clinical Reasoning
This child has tinea capitis (fungal infection of the scalp) that has progressed to kerion formation. The kerion is an intense delayed-type hypersensitivity reaction to the dermatophyte, not a bacterial abscess. Key clues include: alopecia with black dots (broken hairs at follicular openings), boggy tender mass with pustular drainage, posterior cervical lymphadenopathy, exposure to classmates with ringworm and a new kitten (Microsporum canis is often transmitted from cats), and positive Wood's lamp fluorescence. Importantly, topical antifungal therapy alone is ineffective because the fungus infects the hair follicle beyond topical penetration.
Management
- Oral antifungal therapy (REQUIRED): Griseofulvin 20-25 mg/kg/day with fatty food for 6-8 weeks OR Terbinafine for 4-6 weeks (dosed by weight)
- DO NOT incise and drain: Kerion is not a bacterial abscess; I&D is contraindicated and worsens scarring
- Oral corticosteroids: Short course (prednisone 1 mg/kg/day for 1-2 weeks) may reduce inflammation and permanent scarring alopecia
- Antifungal shampoo: Selenium sulfide 2.5% or ketoconazole 2% shampoo twice weekly to reduce spore shedding and transmission
- Treat the source: Veterinary evaluation of the kitten
- Screen household contacts: May be asymptomatic carriers
- School attendance: Can return once treatment initiated (shampoo reduces transmission)
Clinical Image
Image Description: A child with a kerion, showing a boggy, indurated, pustular nodule on the scalp with surrounding alopecia, representing an intense inflammatory response to dermatophyte infection.
Source: Wikimedia Commons URL: https://commons.wikimedia.org/wiki/File:Kerion.jpg License: CC BY-SA 3.0