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For further information, see CMDT Part 6-14: Fungal Infections of the Skin

Key Features

Essentials of Diagnosis

  • Ring-shaped lesions with an advancing scaly border and central clearing or scaly patches with a distinct border

  • Microscopic examination of scrapings or culture confirms the diagnosis

General Considerations

  • The lesions are often on exposed areas of the body such as the face and arms

  • History of exposure to an infected pet (who may have scaly rash or patches of alopecia) may occasionally be obtained, usually indicating Microsporum infection

  • Trichophyton rubrum is the most common pathogen, usually representing extension onto the trunk or extremities of tinea cruris, pedis, or manuum

Clinical Findings

Symptoms and Signs

  • Itching may be present

  • In classic lesions, rings of erythema have an advancing scaly border and central clearing

Differential Diagnosis

  • Psoriasis

  • Systemic lupus erythematosus

  • Secondary syphilis

  • Granuloma annulare

  • Pityriasis rosea

Diagnosis

Diagnostic Procedures

  • The diagnosis should be confirmed by KOH preparation and culture

Treatment

Medications

Table 6–2.Useful topical dermatologic therapeutic agents.

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