Makindo Medical Notes

Introduction

Tinea corporis, also known as ringworm of the body, is a superficial fungal infection of the skin caused by dermatophytes. It affects the arms, legs, and trunk but can occur anywhere on the body. The infection is named "ringworm" due to its characteristic ring-shaped, red, scaly lesions, although no actual worm is involved.

Etiology

Tinea corporis is caused by dermatophyte fungi, which include species from three genera: Trichophyton, Microsporum, and Epidermophyton. Common species involved are:

• Trichophyton rubrum (most common cause).
• Trichophyton mentagrophytes.
• Microsporum canis (often associated with animal contact).

Risk Factors

• Warm and humid environments.
• Close contact with infected individuals or animals (cats, dogs).
• Sharing personal items (e.g., towels, clothing, sports equipment).
• Excessive sweating (hyperhidrosis).
• Immunosuppression (e.g., HIV, diabetes, or long-term corticosteroid use).

Clinical Presentation

• Lesions:
  • Characteristically circular or ring-shaped with a raised, red, scaly border.
  • The center of the lesion may become clear as it grows outward.
  • Multiple lesions may coalesce into large patches.
• Symptoms:
  • Pruritus (itching) is common and can be intense.
  • Mild burning or discomfort in the affected area.
• Common Locations:
  • Arms, legs, chest, back, and occasionally the face.

Typical annular lesions of Ringworm

Diagnosis

Diagnosis of tinea corporis is primarily clinical, but can be confirmed with laboratory testing:

• Clinical Examination: Recognizing the characteristic ring-shaped, scaly lesions with central clearing.
• KOH (Potassium Hydroxide) Preparation: Skin scrapings examined under a microscope for the presence of hyphae.
• Fungal Culture: May be used in persistent or unclear cases to identify the specific fungal species.
• Wood's Lamp: Some fungi (e.g., Microsporum) fluoresce under ultraviolet light, aiding in diagnosis.

Differential Diagnosis

• Psoriasis
• Atopic dermatitis
• Nummular eczema
• Pityriasis rosea
• Granuloma annulare
• Cutaneous lupus erythematosus

Treatment

Management of tinea corporis involves topical or oral antifungal medications:

• Topical Antifungals (first-line for localized infections):
  • Azoles: Clotrimazole, miconazole, ketoconazole.
  • Allylamines: Terbinafine, naftifine.
  • Apply twice daily for 2-4 weeks until the infection clears.
• Oral Antifungals (for widespread or resistant infections):
  • Terbinafine: 250 mg once daily for 2-4 weeks.
  • Itraconazole: 100-200 mg once daily for 2-4 weeks.
  • Griseofulvin: 500-1000 mg daily for 4-6 weeks (less commonly used).
• Supportive Care: Encourage good hygiene, keep skin dry, and avoid sharing personal items.

Prevention

• Avoid direct contact with infected individuals or animals.
• Do not share towels, clothing, or personal items.
• Keep skin clean and dry, especially in warm and humid environments.
• Wear breathable, loose-fitting clothing to reduce moisture accumulation.

Complications

• Spread of infection: Tinea corporis can spread to other areas of the body or to close contacts.
• Secondary bacterial infections: Due to scratching and skin breakdown.
• Tinea Incognito: Misdiagnosis and improper treatment with corticosteroids can mask symptoms and worsen the infection.

Prognosis

With appropriate treatment, tinea corporis generally resolves within 2-4 weeks. However, recurrence is possible, especially if hygiene is poor or predisposing factors are not addressed.

Summary

Tinea corporis is a common superficial fungal infection of the skin. It presents as itchy, ring-shaped lesions with a clear center. Diagnosis is primarily clinical, and treatment involves topical or oral antifungal medications. Prevention involves maintaining good hygiene and avoiding contact with infected individuals or animals. With proper treatment, the prognosis is good, though recurrence can occur.