What is the diagnosis and treatment for scattered skin macules and papules with itchy circular central clearance?

Diagnosis and Treatment of Scattered Itchy Circular Lesions with Central Clearance

The most likely diagnosis is tinea corporis (ringworm), which should be treated with topical antifungal therapy as first-line management. 1

Clinical Diagnosis

The presentation of pruritic, annular (circular), erythematous lesions with central clearing that grow centrifugally is pathognomonic for tinea corporis. 1 This fungal infection characteristically presents as scattered macules and papules with the distinctive ring-shaped appearance and central clearing described. 1

Diagnostic Confirmation

• Perform potassium hydroxide (KOH) examination of skin scrapings from the active border of lesions to confirm fungal elements before initiating treatment. 1
• The active, raised border contains the highest concentration of fungal organisms, making it the optimal site for sampling. 1

Key Differential Diagnoses to Consider

While tinea corporis is most likely, other conditions with annular presentations include:

• Erythema multiforme: Presents with target lesions but typically has minimal pruritus and involves distal extremities preferentially. 2
• Nummular eczema: Shows coin-shaped papulovesicular lesions but lacks the characteristic advancing border with central clearing. 1
• Granuloma annulare: Non-pruritic annular lesions, which distinguishes it from the itchy presentation described. 1
• Pityriasis rosea: Multiple erythematous lesions with raised, scaly borders but generally self-limited and often preceded by a herald patch. 1

Treatment Protocol

First-Line Topical Antifungal Therapy

Apply topical antifungal cream (clotrimazole, miconazole, or terbinafine) twice daily to affected areas and 2-3 cm beyond the visible border for 2-4 weeks. 1 Continue treatment for at least one week after clinical resolution to prevent recurrence.

Symptomatic Management of Pruritus

• Oral antihistamines: Cetirizine or loratadine 10 mg daily (non-sedating), or hydroxyzine 10-25 mg four times daily or at bedtime for more severe itching. 3
• Low-potency topical corticosteroids (hydrocortisone 1-2.5% cream) may be used sparingly for severe pruritus, but should not be used as monotherapy as they can worsen fungal infections. 4, 5

When to Escalate Treatment

If lesions cover >10% body surface area (BSA), consider:

• Non-urgent dermatology referral 3
• Continue topical antifungals with oral antihistamines 3
• May require systemic antifungal therapy (oral terbinafine or itraconazole) for extensive involvement

If lesions cover >30% BSA or fail to respond to topical therapy after 2-3 weeks:

• Same-day dermatology consultation 3
• Consider systemic antifungal therapy
• Rule out immunocompromised state or alternative diagnoses 3

Critical Pitfalls to Avoid

• Do not use topical corticosteroids alone without antifungal coverage, as this will worsen tinea corporis by suppressing local immunity while allowing fungal proliferation. 4
• Do not stop treatment when lesions appear resolved; continue for at least one additional week to prevent recurrence. 1
• Always confirm diagnosis with KOH preparation when possible, as misdiagnosis can lead to inappropriate treatment and disease progression. 1
• Evaluate for tinea pedis, tinea cruris, or onychomycosis as potential sources of autoinoculation requiring concurrent treatment. 1