What is the treatment for an annular rash on the shoulder with an itchy throat that started 1 week prior?

Treatment of Annular Rash on Shoulder with Itchy Throat

This presentation is most consistent with tinea corporis (ringworm), and should be treated with topical antifungal therapy for 2 weeks, specifically a topical azole or allylamine agent applied once or twice daily. 1

Diagnostic Considerations

The annular rash on the shoulder strongly suggests a dermatophyte infection (tinea corporis), which characteristically presents as:

• Erythematous, scaly eruption with annular (ring-shaped) morphology 2, 3
• May or may not be itchy 3
• Asymmetry is an important clinical clue to fungal infection 3

Before initiating treatment, confirm the diagnosis with potassium hydroxide (KOH) preparation of skin scrapings, as this is the gold standard for diagnosis and ensures appropriate therapy. 2, 3, 1

The "itchy throat" that started concurrently is likely unrelated to the skin condition and may represent:

• A separate viral upper respiratory infection 2
• Allergic rhinitis 2
• Coincidental timing with the rash

Treatment Protocol for Tinea Corporis

First-Line Topical Therapy

Treat with topical antifungal agents for 2 weeks minimum, continuing for at least 1 week after clinical clearing of the infection: 1

• Azole antifungals (applied once or twice daily): 1

  • Clotrimazole
  • Miconazole
  • Ketoconazole

• Allylamine antifungals (shorter treatment duration of 1-2 weeks): 1

  • Terbinafine 1% 4, 1
  • Naftifine

Newer allylamine medications require fewer applications and shorter duration compared to azoles. 1

When to Consider Systemic Therapy

Oral antifungal therapy is indicated if: 1

• The infection covers an extensive area of the body
• Topical therapy fails after appropriate duration
• Patient compliance with topical therapy is poor

Adjunctive Measures

Address exacerbating factors: 1

• Reduce skin moisture in affected areas
• Avoid occlusive clothing
• Keep the area clean and dry

Important Clinical Pitfalls

Do not use topical corticosteroids alone, as this will worsen fungal infections. 1 However, if significant inflammation is present, a combination antifungal/steroid agent may be used cautiously for a limited time, as these have potential for causing skin atrophy and other steroid-associated complications. 1

Do not assume the diagnosis without confirmation—other conditions can mimic tinea corporis: 2, 5

• Granuloma annulare (nonscaly annular plaques with indurated borders, typically self-resolving) 2, 5
• Pityriasis rosea (fawn-colored lesions along skin cleavage lines) 2
• Subacute cutaneous lupus erythematosus (on sun-exposed surfaces) 2
• Urticaria (evanescent plaques without scale) 2

The key differentiating feature is that tinea corporis has scale, while granuloma annulare and urticaria do not. 2, 5

Management of the Throat Symptoms

The itchy throat requires separate evaluation and is likely unrelated to the dermatophyte infection. Consider:

• Symptomatic treatment with antihistamines if allergic in nature 6
• Observation for development of other upper respiratory symptoms
• No specific treatment needed if mild and self-limited

If the throat symptoms worsen or are accompanied by systemic signs (fever, difficulty swallowing, respiratory distress), evaluate for alternative diagnoses including streptococcal pharyngitis or allergic reaction. 6