What could be causing scaly, light brown, circular patches on my forehead near the scalp and cheek?

Scaly, Light Brown, Circular Patches on Forehead and Cheek

The most likely diagnosis is tinea capitis (scalp ringworm) extending to the facial skin, which requires laboratory confirmation with scalp scrapings or hair plucking followed by systemic antifungal therapy if confirmed. 1

Clinical Presentation and Differential Diagnosis

Your description of scaly, light brown, circular patches near the scalp line and on the cheek is highly suggestive of a dermatophyte (fungal) infection, specifically:

• Tinea capitis with facial extension: Ectothrix Microsporum infection characteristically produces fine scaling with circular patches that appear dull grey to light brown, with minimal inflammation when caused by anthropophilic fungi like M. audouinii 1
• The circular, scaly nature with light brown coloration fits the classic presentation of dermatophyte infection affecting the scalp margin 1
• Facial involvement can occur as extension from scalp infection or as tinea faciei 1

Alternative diagnoses to consider:

• Seborrheic dermatitis: Can present as scaly patches on the scalp, forehead, and face, but typically appears more diffuse and greasy rather than distinctly circular 1
• Contact dermatitis: Would require exposure history to specific allergens or irritants, and typically presents with more erythema and pruritus 1
• Atopic dermatitis: Usually involves other body areas and has a different distribution pattern in adults 2

Immediate Diagnostic Steps

Laboratory confirmation is essential before starting treatment:

• Collect specimens by scalp scraping using a blunt scalpel to remove hair and scalp scale from the affected areas 1
• If available, pluck hairs from the border of the lesions, particularly any that appear broken or dull 1
• Submit specimens for both microscopy (potassium hydroxide preparation) and fungal culture on Sabouraud agar 1
• Culture plates should be incubated for at least 2 weeks to identify the causative dermatophyte species 1

Clinical examination should include:

• Examination under Wood's lamp: Some Microsporum species (particularly M. canis) will fluoresce green, though many common species do not fluoresce 1
• Assessment for "black dots" (broken hair stubs), which would suggest endothrix infection with Trichophyton species 1
• Evaluation for signs of inflammation, pustules, or kerion formation 1

Treatment Algorithm

If tinea capitis is confirmed:

• Systemic antifungal therapy is mandatory - topical treatments alone are insufficient for scalp infections 1
• The specific antifungal agent and duration should be guided by the identified organism from culture results 1
• Common first-line options include griseofulvin or terbinafine, with choice depending on the specific dermatophyte species 1
• Treatment typically continues for 6-8 weeks or longer until mycological cure is documented 1

Post-treatment monitoring:

• Send follow-up specimens after completing therapy to confirm mycological clearance 1
• Clinical improvement alone is insufficient - microscopy and culture must be negative 1

Critical Pitfalls to Avoid

• Do not treat empirically without laboratory confirmation: The clinical diagnosis may be accurate, but identifying the causative organism directs appropriate systemic therapy 1
• Do not use topical antifungals alone: Scalp infections require systemic treatment because topical agents cannot adequately penetrate hair follicles 1
• Do not confuse with seborrheic dermatitis: Scalp involvement in tinea capitis can mimic dandruff or seborrheic dermatitis, leading to delayed diagnosis and inappropriate treatment 1
• Do not overlook potential contacts: If fungal infection is confirmed, consider screening household members and identify the source (human-to-human transmission or animal contact with zoophilic species) 1

When to Refer

Consider dermatology referral if:

• Diagnosis remains uncertain after initial evaluation 2
• No improvement after 2 weeks of appropriate systemic antifungal therapy 1
• Development of severe inflammatory response (kerion) requiring additional management 1
• Recurrent infections despite adequate treatment 1