Erythema marginatum
Background
- A rare, non-pruritic rash that is one of the major Jones criteria for acute rheumatic fever (ARF)
- Strongly associated with post-streptococcal autoimmune responses, particularly in children and adolescents
- Though uncommon in the ED, its recognition is important because it may be an early or subtle clue to a potentially serious systemic illness, especially when accompanied by joint pain, fever, or cardiac involvement.
Clinical Features
Appearance
- Pink to red, serpiginous or annular macules or patches
- Central clearing, with raised margins
- May coalesce into polycyclic shapes
Distribution
- Typically found on trunk and proximal limbs
- Spares the face
Characteristics
- Transient (lesions may appear and disappear over hours)
- Non-pruritic, often unnoticed by the patient
- Usually occurs early in the course of ARF
Differential Diagnosis
- Urticaria (usually pruritic and shorter-lived lesions)
- Tinea corporis (scaly border; longer duration)
- Erythema multiforme (target lesions; mucosal involvement)
- Erythema migrans (Lyme disease; often has history of tick exposure)
- Erythema annulare centrifugum
- Pityriasis rosea (typically has herald patch, follows cleavage lines)
- Systemic lupus erythematosus (may produce annular lesions)
- Drug eruptions
Evaluation
Workup
- Rapid strep test or throat culture
- Anti-streptolysin O (ASO) or anti-DNase B titers
- CBC (may show leukocytosis)
- ESR/CRP (typically elevated in ARF)
- ECG (look for PR prolongation)
- Echocardiogram if there are signs/symptoms of carditis
Diagnosis
Diagnosis is clinical and often supportive in the context of other signs of acute rheumatic fever. Confirm diagnosis of ARF using revised Jones criteria:
- Major criteria: migratory arthritis, carditis, chorea, erythema marginatum, subcutaneous nodules
- Minor criteria: fever, arthralgia, elevated ESR/CRP, prolonged PR interval
- A diagnosis of ARF typically requires 2 major or 1 major + 2 minor criteria, plus evidence of recent group A Streptococcus infection.
Management
- Treat underlying acute rheumatic fever:
- Penicillin or other antibiotics to eradicate streptococcal infection
- Aspirin or NSAIDs for arthritis
- Corticosteroids in severe carditis
- Skin lesions themselves do not require direct treatment, as they are self-limited
- Patient and family education about recurrence prevention and long-term prophylaxis
Disposition
Discharge
- If well-appearing, hemodynamically stable, and has a plan for follow-up with cardiology and primary care for rheumatic fever management
Admit
- There is suspected or confirmed carditis
- Patient is febrile, toxic, or has signs of systemic involvement
- Requires workup and treatment initiation for suspected acute rheumatic fever