Erythema Multiforme Minor Diagnosis and Management

Key Diagnostic Features

• The presence of target-like lesions, which are pathognomonic for Erythema Multiforme (EM) and not characteristic of urticaria, is a critical diagnostic feature, as noted by the British Journal of Dermatology 2
• Lesions that persist and evolve over days, rather than resolving within 24 hours as expected with urticaria, are consistent with EM Minor, according to the Journal of Allergy and Clinical Immunology and the British Journal of Dermatology 1, 2

Differential Diagnoses

• Acute urticaria can be distinguished from EM Minor by its pruritic wheals that resolve within 24 hours, individual lesions that blanch completely, and lack of target morphology, as described by the Journal of Allergy and Clinical Immunology and the British Journal of Dermatology 1, 2, 3
• A skin biopsy can show interface dermatitis with keratinocyte necrosis and lymphocytic infiltrate in EM, dermal edema and perivascular infiltrate without keratinocyte damage in urticaria, and variable non-specific perivascular lymphocytic infiltrate in viral exanthem, as noted by the British Journal of Dermatology 2, 3

Clinical Management

• The American Academy of Dermatology recommends supportive care only for EM Minor, with no specific treatment required, and identification and avoidance of potential triggers, such as recent food exposure 1, 2