Physical Examination of Tinea Capitis
The physical examination of tinea capitis should systematically assess for specific clinical patterns including non-inflammatory presentations (grey patch, black dot, diffuse scale) and inflammatory variants (kerion, favus), followed by Wood's lamp examination and dermoscopy when available, with specimen collection for mycological confirmation being essential before initiating treatment. 1
Clinical Presentation Patterns to Identify
Non-Inflammatory Variants
Grey patch tinea capitis: Look for single or multiple patches of alopecia with fine scale and broken hairs, typically caused by ectothrix infections (Microsporum species); the inflammatory response is minimal with anthropophilic fungi but more intense with zoophilic species like M. canis 1
Black dot pattern: Examine for patches of alopecia with fine scale studded with broken-off, swollen hair stubs at the scalp surface, creating a characteristic "black dot" appearance; this indicates endothrix infection with Trichophyton species (T. tonsurans, T. violaceum, T. soudanense) 1
Diffuse scale presentation: Assess for generalized, diffuse scaling resembling dandruff with minimal or absent alopecia 1
Inflammatory Variants
Kerion celsi: Identify painful, boggy, inflammatory masses with associated alopecia, solitary or multiple plaques studded with pustules and matted with thick crust; palpate for regional lymphadenopathy which is common 1
Diffuse pustular variant: Look for patchy alopecia coexisting with scattered pustules or low-grade folliculitis, often with painful regional lymphadenopathy 1
Favus: Recognize yellow, crusted, cup-shaped lesions ("scutula") composed of hyphae and keratin debris developing around follicular openings; this chronic inflammatory variant is most common in Middle East and North Africa with T. schoenleinii and may result in cicatricial alopecia 1
Adjunctive Examination Techniques
Wood's Lamp Examination
- Use Wood's lamp to identify fluorescence in M. canis infections and favus (T. schoenleinii) 1
- Note that T. tonsurans (the most common cause in North America) does NOT fluoresce, limiting the utility of this test in current epidemiology 2
- Affected hairs identified by fluorescence can be specifically plucked for specimen collection 1
Dermoscopy
- Utilize dermoscopy as a highly sensitive adjunctive diagnostic tool to visualize black dot hair stubs more clearly 1, 3
- Look for "comma-shaped" hairs in white children with ectothrix infection 1
- Identify "corkscrew hairs" in Afro-Caribbean children with tinea capitis 1
Specimen Collection During Physical Exam
Multiple sampling methods increase diagnostic yield and should be performed during the initial examination. 1
Collection Techniques
Scalp scraping: Use a blunt scalpel to remove hair and scalp scale from affected areas 1
Hair plucking: Pluck hairs from affected areas, particularly those showing fluorescence under Wood's lamp in M. canis infections 1
Brush sampling (cytobrush): This method improves sensitivity and time to positive culture, causes less discomfort to children with soft bristles, and is available as a sterile device; however, it only permits culture, not microscopy 1
Gauze swabs: An equally effective and often more convenient sampling method 1
Specimen storage: Collect specimens in paper or card packs, NOT plastic 1
Associated Findings to Document
Regional lymphadenopathy: Palpate for enlarged lymph nodes, particularly in inflammatory variants 1
"Id" reaction (dermatophytid): Examine for pruritic, papular eruptions, particularly around the outer helix of the ear, which may accompany treatment initiation; this represents a cell-mediated host response and should not be confused with drug reaction 1
Secondary bacterial infection: Assess for signs of superimposed bacterial infection, especially in kerion presentations 1
Laboratory Confirmation Strategy
Although clinical diagnosis is often accurate, laboratory confirmation is advisable to isolate the causal organism and direct systemic therapy choice. 1
Microscopy: Mount specimens in 10-30% potassium hydroxide with or without calcofluor for examination by light or fluorescence microscopy to identify hyphae and/or arthroconidia; note that sensitivity is not high 1
Culture: Culture all specimens on Sabouraud agar with at least one plate containing cycloheximide, incubated for at least 2 weeks (3 weeks if T. verrucosum suspected with cattle exposure) 1
Post-treatment sampling: Send samples after treatment to ensure mycological clearance, as clinical improvement alone is insufficient 1, 4
Treatment Initiation Considerations
Oral systemic antifungal therapy is required for tinea capitis, as topical therapy alone does not penetrate hair follicles adequately. 4, 3
In high-risk populations, consider starting treatment empirically while awaiting culture results (which take 2-4 weeks) to prevent further spread 1
Griseofulvin remains the treatment of choice for Microsporum infections, while terbinafine is preferred for Trichophyton infections 4, 5
Adjunctive antifungal shampoos reduce spore transmission but are not curative alone 4
Common Pitfalls
Misdiagnosing kerion as bacterial abscess: Always consider tinea capitis in inflammatory scalp masses, though secondary bacterial infection should not be overlooked 1
Stopping treatment based on clinical improvement: The endpoint must be mycological cure, not clinical response; continue treatment until mycological clearance is documented 6, 4
Confusing "id" reaction with drug allergy: The dermatophytid eruption after treatment initiation does not warrant cessation of antifungal therapy 1
Relying solely on Wood's lamp: This is only useful for specific species (M. canis, T. schoenleinii) and will miss the most common current pathogen, T. tonsurans 2