Wood light examination of erythrasma

Diagnosis: Wood light examination of erythrasma

coral-red fluorescence of lesions

Clinical Presentation

coral-red fluorescence of lesions

Clinical History

Submitted by Alaa Saad. Originally posted August 29, 2010.

Treatment

See case discussion.

Differential Diagnosis

• Tinea cruris • Inverse psoriasis • Intertrigo • Contact dermatitis • Candidiasis (cutaneous) • Seborrheic dermatitis

Key Learnings

• Caused by Corynebacterium minutissimum — bacterial infection, NOT fungal • Well-demarcated, brown-red, slightly scaly patches in intertriginous areas (groin, axillae, toe web spaces) • Coral-red fluorescence under Wood lamp — due to coproporphyrin III production • Often confused with tinea cruris — KOH negative distinguishes • More common in diabetes, obesity, warm/humid climates • Toe web space erythrasma is the most common form

Tags: wood, light, examination, erythrasma, alaa saad