II. Signs: Ring-shaped or Annular Lesion

  1. Characteristics
    1. Circular or oval Macule or patch
    2. Erythematous outer border
    3. Central clearing

V. Labs

  1. Potassium Hydroxide slide preparation
    1. Evaluate for Fungal Skin Infection
  2. Biopsy Indications
    1. Pityriasis Rosea lasting longer than 3 months
    2. Individual Urticarial lesions that last longer than 24 hours
      1. Evaluate for Leukocytoclastic Vasculitis
    3. Suspected uncommon cause
      1. IgA Vasculitis
      2. Sarcoidosis
      3. Leprosy
  3. PCR or Serology Indications
    1. Erythema Migrans (Lyme Disease)
      1. Clinical diagnosis if typical findings are present
    2. Rapid Plasma Reagin or RPR (Secondary Syphilis)
    3. Antinuclear Antibody

VI. Management: Empiric Therapy for Common Causes

  1. General Measures
    1. Skin Lubricants
    2. Antihistamines
    3. Eliminate possible causes (e.g. new medications, topical irritants or allergans)
  2. Antifungal indications
    1. Tinea Corporis
      1. First line: Clotrimazole
      2. Second-line: Butenafine, Naftifine
  3. Corticosteroid indications
    1. Plaque Psoriasis or Pustular Psoriasis
      1. First-line: Potent Topical Corticosteroids (Clobetasol or Fluocinonide ointment)
      2. Second-line: Calcipotriene or Tazarotene, UVA/UVB, Biologic Agents
    2. Lichen Planus
      1. Purple, planar, polygonal, pruritic Papules and Plaques (6Ps) on ankle, volar wrist, Oral Mucosa
      2. First-line: Potent Topical Corticosteroids (Clobetasol or Fluocinonide ointment) or Systemic Corticosteroids
      3. Second-line: UVA/UVB
    3. Nummular Eczema
      1. First-Line: Skin Lubricants
      2. Second-Line: Topical Corticosteroids
    4. Pityriasis Rosea
      1. First-Line: No treatment modifies course consistently
      2. Pruritus symptomatic management: Topical Corticosteroids, Antihistamines
  4. Antibiotic indications
    1. Suspected Erythema Migrans (Lyme Disease)
      1. Lesions >5 cm up to 20 cm, 3-30 days after Tick Bite in endemic areas)
      2. Doxycycline is preferred (Amoxicillin and Cefuroxime have also been used)
  5. Antiviral indications
    1. Erythema Multiforme
      1. Valtrex (or other antiviral) if recurrent episodes (up to 90% may be due to HSV)
    2. Pityriasis Rosea
      1. Acyclovir may be effective (HSV is among possible causes)
      2. Ganguly (2014) J Clin Diagn Res 8(5): YC01-YCO4 [PubMed]
      3. Rassai (2011) J Eur Acad Dermatol Venereol 25(1): 24-6 [PubMed]
  6. UVA/UVB indications
    1. Plaque Psoriasis or Pustular Psoriasis
    2. Lichen Planus
    3. Pityriasis Rosea
      1. UVB May be effective
      2. Valkova (2004) J Eur Acad Dermatol, Venereol 18(1): 111-2 [PubMed]

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