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Diagnosis: Tinea Corporis (Ringworm)
The image shows multiple ring-shaped (annular), erythematous, scaly lesions on the back and shoulder, with central clearing and an advancing red border. This is the hallmark appearance of Tinea corporis - a superficial fungal (dermatophyte) skin infection. Despite the name "ringworm," no worm is involved.
Cause
Fungal infection by dermatophytes - mold-like fungi that infect keratin in the skin. The most common species are:
| Organism | Common Source |
|---|---|
| Trichophyton rubrum | Most common overall; human-to-human spread |
| Microsporum canis | Contact with infected pets (cats/dogs) |
| Trichophyton mentagrophytes | Animals, soil contact |
How it spreads:
- Direct skin-to-skin contact with an infected person or animal
- Contact with contaminated objects (towels, clothing, bedding)
- Living in hot, humid environments (sweat accelerates growth)
- Immunosuppression (widespread tinea corporis can be a sign of HIV/AIDS)
- Use of topical corticosteroids (can cause "tinea incognita" - atypical widespread tinea)
Treatment
Localized disease (like what's shown in the image):
Topical antifungals applied to the lesion AND 1-2 cm beyond the border:
| Drug | Brand | Duration |
|---|---|---|
| Terbinafine 1% cream | Lamisil | 1-2 weeks once daily |
| Clotrimazole 1% cream | Lotrimin | 2-4 weeks, twice daily |
| Miconazole 2% cream | Micatin | 2-4 weeks, twice daily |
| Ketoconazole 2% cream | Nizoral | 2-4 weeks, once daily |
| Econazole 1% cream | Spectazole | 2-4 weeks, once daily |
Terbinafine is generally preferred because it is fungicidal (kills the fungus) vs. others that are fungistatic, and it works fastest (1 week for mild cases).
Extensive or severe disease (oral therapy):
- Terbinafine 250 mg/day x 2-4 weeks
- Itraconazole 100-200 mg/day x 2-4 weeks
- Fluconazole 150-300 mg weekly x 4-6 weeks
Oral treatment is needed if:
- Lesions are widespread (like this case with multiple lesions)
- Patient is immunocompromised
- Topical therapy has failed
- Hair follicles are involved
Important - What NOT to do:
- Do NOT use topical steroids (like hydrocortisone) alone or combination steroid/antifungal products such as clotrimazole/betamethasone - this suppresses the immune response, masks the infection, and causes the fungus to spread widely ("tinea incognita")
Diagnosis Confirmation
A doctor can confirm by:
- KOH (potassium hydroxide) preparation - skin scraping examined under microscope shows branching hyphae
- Fungal culture - definitive but takes 1-2 weeks
Prevention / Hygiene Tips
- Keep skin clean and dry
- Avoid sharing towels, clothing, or combs
- Treat household contacts and infected pets
- Change clothes and shower after sweating
- Wash bedsheets/clothing in hot water during treatment
Important disclaimer: This information is educational only. Given the multiple and somewhat large lesions visible in the image, a doctor visit is recommended - especially since oral antifungal therapy may be needed for widespread infection. Do not self-treat with steroid creams.
- Andrews' Diseases of the Skin, Clinical Dermatology | Tinea Corporis section
- Harrison's Principles of Internal Medicine 22E (2025) | Dermatophyte Infections
- CDC Ringworm Treatment
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