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Erythema multiforme is an immune-mediated disorder characterized by the presence of distinctive target lesions on the skin (primarily in acral regions) and/or mucous membranes.
The exact pathophysiology of erythema multiforme is not fully understood, but it is believed to be an immune reaction triggered by various factors. Infections, particularly HSV, are the most common triggers. Other viruses, such as HCV, Coxsackievirus, and EBV, as well as Mycoplasma pneumoniae, certain medications, and vaccines have also been implicated.
The incidence of erythema multiforme is believed to be 0.01-1% annually, most commonly affecting individuals aged 18-30 years.
Clinically, erythema multiforme presents with symmetrically distributed target lesions on the extremities and trunk. These lesions are characterized by concentric zones of color change. The severity of erythema multiforme can vary widely, from mild forms with only skin involvement to severe forms that affect multiple mucous membranes and can be life-threatening.
Prognosis and risk of recurrence
The prognosis for erythema multiforme is generally favorable. Most cases are self-limiting and resolve within weeks to months without long-term complications.
The following summarized guidelines for the evaluation and management of erythema multiforme are prepared by our editorial team based on guidelines from the American Academy of Family Physicians (AAFP 2019) and the Infectious Diseases Society of America (IDSA 2014).
1.Screening and diagnosis
Diagnosis: as per AAFP 2019 guidelines, suspect erythema multiforme in patients with a target or iris lesion characterized by three concentric segments: a dark center surrounded by a lighter pink ring, both surrounded by a red ring.
Topical corticosteroids: offer topical corticosteroids for symptomatic management in patients with acute, uncomplicated erythema multiforme.
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Secondary prevention: offer continuous prophylactic antiviral therapy in patients with recurrent HSV-associated erythema multiforme.
4.Follow-up and surveillance
Indications for referral: refer patients with any ocular erythema multiforme involvement urgently for ophthalmologic consultation.