Clinical Assessment
Most likely diagnosis: Tinea Corporis (Ringworm)
The lesion in the image is highly consistent with tinea corporis - a superficial dermatophyte infection of glabrous (non-hairy) skin. Here is the breakdown:
What the Image Shows
| Feature | Observation |
|---|
| Shape | Well-demarcated, oval/annular plaque |
| Center | Hyperpigmented, grayish-brown, dry - showing central clearing/resolution |
| Border | Raised, reddish-brown erythematous rim |
| Surface | Classic "collarette of scale" - peeling epidermal tissue at the periphery |
| Location | Lateral torso/flank, above waistline |
| Patient | Appears to be a child |
This matches textbook description almost exactly: "The classic presentation is that of an annular ('ringworm'-like) or serpiginous plaque with scale across the entire active erythematous border. The border advances centrifugally. The center of the plaque is usually scaly but may exhibit complete clearance." - Fitzpatrick's Dermatology
Here is a textbook reference image of tinea corporis for comparison:
Why Tinea Corporis?
- Annular morphology with central clearing and an active, scaly, raised border - the hallmark
- Collarette of peeling scale at the periphery (desquamating epidermal edge)
- Location on glabrous skin (torso/flank) - by definition tinea corporis is dermatophytosis of glabrous skin excluding palms, soles, and groin
- Child patient - children commonly acquire zoophilic strains (e.g., Microsporum canis from dogs/cats); common organisms also include Trichophyton rubrum and T. tonsurans
- The central hyperpigmentation with dry, slightly shiny surface suggests the lesion is in a resolving or partially treated phase
Differential Diagnosis to Consider
| Category | Conditions |
|---|
| Most Likely | Tinea corporis, nummular eczema, erythema annulare centrifugum |
| Consider | Psoriasis (plaque), contact/atopic dermatitis, pityriasis rosea |
| Rule Out | Subacute cutaneous lupus (in adults), secondary syphilis, mycosis fungoides |
Recommended Management
Confirm with: KOH preparation (potassium hydroxide scraping of the scaly border) - will show fungal hyphae. Wood's lamp may fluoresce with M. canis.
For an isolated plaque (topical antifungal - first line):
- Terbinafine 1% cream - apply twice daily for 1-2 weeks (allylamine - fungicidal)
- Clotrimazole 1% cream - apply twice daily for 2-4 weeks (imidazole)
- Miconazole 2% cream - twice daily for 2-4 weeks
- Extend 1-2 cm beyond the visible border; treat for at least 1-2 weeks after clinical resolution
Oral antifungals (if widespread, inflamed, or unresponsive to topicals):
- Terbinafine 250 mg/day x 2-4 weeks
- Griseofulvin (especially in children, particularly for M. canis)
- Itraconazole or fluconazole as alternatives
(Source: Fitzpatrick's Dermatology; Goldman-Cecil Medicine; Andrews' Diseases of the Skin)
Important Notes
- Avoid applying topical corticosteroids alone - this can suppress inflammation and mask the infection ("tinea incognito"), worsening the underlying fungal infection
- Keep the skin dry; avoid occlusive clothing
- Check household pets or close contacts for infection sources (zoophilic transmission in children)
- If no improvement after 2-4 weeks of topical treatment, refer to dermatology
Disclaimer: This is a clinical image analysis for educational purposes. A definitive diagnosis requires in-person examination, KOH microscopy, and/or fungal culture. Please consult a healthcare provider for treatment decisions.