From the Guidelines
Ringworm on physical examination appears as a circular or ring-shaped rash with a raised, scaly border and central clearing, as described in the guidelines for the management of tinea capitis 1. The affected skin is typically red, inflamed, and may be itchy or burning. The lesions can vary in size from a few millimeters to several centimeters in diameter.
- The borders are often more active with redness, scaling, and sometimes small blisters or pustules, while the center may appear to be healing.
- Multiple lesions can occur and may overlap.
- The appearance can differ based on the body location - on the scalp, it may cause patches of hair loss with scaling; on the feet (athlete's foot), it presents as scaling and cracking between toes; and on nails, it causes thickening, discoloration, and brittleness. Diagnosis is primarily clinical based on the characteristic appearance, but can be confirmed with a KOH preparation showing branching hyphae under microscopy or with fungal culture, as noted in the british association of dermatologists' guidelines for the management of tinea capitis 2014 1. Ringworm is caused by dermatophyte fungi that infect the outer layers of skin, hair, and nails, thriving in warm, moist environments and spreading through direct contact with infected individuals, animals, or contaminated objects.
- A kerion, a painful, boggy, inflammatory mass with associated alopecia, may be present in some cases, particularly with zoophilic, large-spore ectothrix species 1.
- Favus, a chronic, inflammatory tinea capitis, may also occur, characterized by yellow, crusted, cup-shaped lesions (‘scutula’) composed of hyphae and keratin debris 1.
From the Research
Physical Exam Findings of Ringworm
The physical exam findings of ringworm, also known as tinea corporis, typically include:
- A well-demarcated, sharply circumscribed, oval or circular, mildly erythematous, scaly patch or plaque with a raised leading edge 2
- Mild pruritus is common 2
- The lesion may grow centrifugally, with central clearing 3
Diagnostic Considerations
The diagnosis of ringworm is often clinical, but can be confirmed by:
- Potassium hydroxide examination of skin scrapings 2, 3
- Fungal culture, which is the gold standard for diagnosing dermatophytosis 2
- Dermoscopy, a non-invasive diagnostic tool 2
Differential Diagnoses
Ringworm can be mistaken for other annular lesions, including: