II. Signs: Ring-shaped or Annular Lesion
- Characteristics
- Circular or oval Macule or patch
- Erythematous outer border
- Central clearing
III. Causes: Common
- Tinea Corporis or Ringworm (most common adult cause)
- Pityriasis Rosea
- Urticaria
- Erythema Annulare Centrifugum
- Erythema Chronicum Migrans (Lyme Disease)
- Erythema Multiforme
- Plaque Psoriasis, Pustular Psoriasis or Guttate Psoriasis
- Nummular Eczema
- Annular Lichen Planus
IV. Causes: Uncommon
V. Labs
-
Potassium Hydroxide slide preparation
- Evaluate for Fungal Skin Infection
- Biopsy Indications
- Pityriasis Rosea lasting longer than 3 months
- Individual Urticarial lesions that last longer than 24 hours
- Evaluate for Leukocytoclastic Vasculitis
- Suspected uncommon cause
- PCR or Serology Indications
- Erythema Migrans (Lyme Disease)
- Clinical diagnosis if typical findings are present
- Rapid Plasma Reagin or RPR (Secondary Syphilis)
- Antinuclear Antibody
- Erythema Migrans (Lyme Disease)
VI. Management: Empiric Therapy for Common Causes
-
General Measures
- Skin Lubricants
- Antihistamines
- Eliminate possible causes (e.g. new medications, topical irritants or allergans)
-
Antifungal indications
- Tinea Corporis
- First line: Clotrimazole
- Second-line: Butenafine, Naftifine
- Tinea Corporis
-
Corticosteroid indications
- Plaque Psoriasis or Pustular Psoriasis
- First-line: Potent Topical Corticosteroids (Clobetasol or Fluocinonide ointment)
- Second-line: Calcipotriene or Tazarotene, UVA/UVB, Biologic Agents
- Lichen Planus
- Purple, planar, polygonal, pruritic Papules and Plaques (6Ps) on ankle, volar wrist, Oral Mucosa
- First-line: Potent Topical Corticosteroids (Clobetasol or Fluocinonide ointment) or Systemic Corticosteroids
- Second-line: UVA/UVB
- Nummular Eczema
- First-Line: Skin Lubricants
- Second-Line: Topical Corticosteroids
- Pityriasis Rosea
- First-Line: No treatment modifies course consistently
- Pruritus symptomatic management: Topical Corticosteroids, Antihistamines
- Plaque Psoriasis or Pustular Psoriasis
-
Antibiotic indications
- Suspected Erythema Migrans (Lyme Disease)
- Lesions >5 cm up to 20 cm, 3-30 days after Tick Bite in endemic areas)
- Doxycycline is preferred (Amoxicillin and Cefuroxime have also been used)
- Suspected Erythema Migrans (Lyme Disease)
-
Antiviral indications
- Erythema Multiforme
- Pityriasis Rosea
- Acyclovir may be effective (HSV is among possible causes)
- Ganguly (2014) J Clin Diagn Res 8(5): YC01-YCO4 [PubMed]
- Rassai (2011) J Eur Acad Dermatol Venereol 25(1): 24-6 [PubMed]
- UVA/UVB indications
- Plaque Psoriasis or Pustular Psoriasis
- Lichen Planus
- Pityriasis Rosea
- UVB May be effective
- Valkova (2004) J Eur Acad Dermatol, Venereol 18(1): 111-2 [PubMed]