Erythema marginatum

Background

Erythema marginatum is a rare, non-pruritic rash that is one of the major Jones criteria for acute rheumatic fever (ARF). It is 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