Tinea Capitis Kerion

Kerion is a severe inflammatory form of tinea capitis in which a hypersensitivity reaction to dermatophytes produces a boggy, painful mass with pustules and hair loss. It affects mainly school aged children.

• Organisms: zoophilic (Microsporum canis, Trichophyton verrucosum, T. mentagrophytes) and anthropophilic species (T. violaceum, T. tonsurans, M. audouinii), the latter common in East Africa.
• Transmission by contact, shared combs, hats, bedding, and animals.

Tender, boggy, erythematous swelling studded with follicular pustules and purulent discharge, matted hair that pulls out easily, regional lymphadenopathy, sometimes fever.

• Scalp alopecia, occipital and cervical nodes, id reaction.
• Differential diagnosis: bacterial scalp abscess, folliculitis decalvans, dissecting cellulitis, pyoderma, carbuncle, impetigo, discoid lupus, Langerhans cell histiocytosis, scalp psoriasis, alopecia areata, malignancy.
• Complications: scarring alopecia, secondary bacterial infection, id reaction, cervical lymphadenitis, fever, cellulitis, psychological distress.

Clinical, confirmed by mycology.

• Hair pluck and scalp scraping for KOH microscopy and fungal culture; dermoscopy (comma, corkscrew hairs); Wood lamp (green fluorescence in Microsporum, absent in Trichophyton).
• Bacterial swab if purulent; full blood count if systemically unwell.
• Avoid incision and drainage.

Systemic antifungal treatment is essential, as topical therapy does not penetrate the hair follicle.

• Supportive: pain relief with paracetamol 15 mg/kg every 6 hours, do not shave or incise, wash combs, hats and bedding, avoid sharing, examine and treat family members and animals.
• Pharmacological: griseofulvin micronised 20 to 25 mg/kg/day (ultramicrosize 10 to 15 mg/kg/day) with fatty food for 6 to 8 weeks until mycological cure; or terbinafine for 4 weeks in Trichophyton infection (under 20 kg 62.5 mg, 20 to 40 kg 125 mg, over 40 kg 250 mg daily), 6 to 8 weeks for Microsporum; or fluconazole 6 mg/kg daily for 3 to 6 weeks; or itraconazole 5 mg/kg daily for 4 to 6 weeks. Ketoconazole 2 percent or selenium sulfide 2.5 percent shampoo twice weekly for 4 weeks to reduce spore shedding. In severe painful kerion add prednisolone 1 mg/kg daily for 10 to 14 days to limit scarring. Flucloxacillin 25 mg/kg/day in four divided doses for 7 days only if secondary bacterial infection.
• Procedures: none; no surgical drainage.
• Special groups: pregnancy and breastfeeding, griseofulvin is contraindicated and fluconazole is avoided, and treatment is deferred or limited to shampoo; liver disease, avoid oral azoles and terbinafine; HIV, longer therapy and exclude other causes; adults, rare and consider immunosuppression.
• Red flags: widespread inflammation with fever, no improvement after 2 weeks, signs of liver injury on terbinafine or griseofulvin, spreading cellulitis, scarring alopecia.
• Follow-up: review every 2 weeks; repeat mycology at 6 to 8 weeks; baseline liver tests for courses over 6 weeks; school return allowed once treatment is started.