erythrasma

Introduction

From Greek 'red spot'.

Chronic superficial bacterial infection of the skin.

Etiology

• Corynebacterium minutissimum
• predisposing factors
  • diabetes
  • warm, humid climate
  • prolonged occlusion of skin
  • maceration

Clinical manifestations

• macules, generally large & scaling, sharply marginated
• pink/red to brownish red in color
• sites of predilection
  • intertriginous areas of toes, groin & axillae
  • skin folds: groin, subpanniculus, intergluteal, inframammary
• mimics dermatophyte infection
• generally asymptomatic, but may cause burning sensation or pruritus
• interdigital lesions are erosive with collarette-like scale
• lesions may consist of confluent patches or scattered, discrete lesions
• skin often has thin, wrinkled appearance similar to cigarette paper

* images

Laboratory

• Wood's lamp: coral-red fluorescence
  • may not be present if patient has recently bathed
• direct microscopic examination of 10% KOH-treated skin scrapings not helpful
• bacterial culture:
  • rule out Staphylococcus aureus or group A streptococcal infection

Differential diagnosis

• dermatophytosis
• cutaneous candidiasis
• pityriasis versicolor
• inverse pattern psoriasis
• seborrheic dermatitis
• pitted keratolysis (Micrococcus sedentarius)
  • manifests as scale & pitting of the skin surface
  • involved areas are white when stratum corneum is fully hydrated
  • toe webs, balls or heel of foot in contact with shoe
  • foot odor (malodorous)
  • hyperhidrosis
  • no hyphae in 10% KOH preparations from skin scrapings
  • Wood's lamp: negative for coral-red fluorescence (erythrasma)
• intertrigo

Management

• topical fusidic acid is the most effective treatment
  • clarithromycin single dose with better patient medication compliance
  • erythromycin inferior to single dose clarithromycin
    • topical erythromycin solution BID for 7 days
    • erythromycin 250 mg PO QID for 14 days
• topical clindamycin
• oral tetracycline
• benzoyl peroxide (2.5%) gel; apply daily for 7 days
• prevention:
  • benzoyl peroxide
  • correct predisposing causes
    • relapses occur if predisposing causes are not corrected

More general terms

• bacterial infection
• skin infection

Additional terms

• Corynebacterium minutissimum