User:Mr. Ibrahem/Erythema multiforme

Not to be confused with erythema migrans, though both may involve target lesions

Erythema multiforme
Other names	Erythema exudativum multiforme
Erythema multiforme minor of the hands (note the blanching centers of the lesion)
Specialty	Dermatology
Symptoms	Target lesions, fever, joint pain
Usual onset	Within 72 hrs
Duration	Up to 6 wks
Types	Minor, major
Risk factors	Infections: Herpes simplex, cytomegalovirus, Epstein-Barr virus, SARS-CoV-2 Medications: NSAIDs, antibiotics, vaccines Other: Inflammatory bowel disease, leukemia, other cancers
Diagnostic method	Based on symptoms
Differential diagnosis	Hives, pemphigus, Stevens-Johnson syndrome
Treatment	Based on trigger, supportive care
Prognosis	Generally good
Frequency	Uncommon

Erythema multiforme (EM) is a skin condition that classically appears as target lesions. The skin or mouth can be involved. These come on over a couple of days and resolve within 3 to 6 weeks. Often they are most clearly seen on the palms and soles. Other symptoms may include fever and joint pain. Some have recurrent episodes.

The most common trigger is a herpes simplex (HSV) infection. Other triggers may include infections such as cytomegalovirus, Epstein-Barr virus, and SARS-CoV-2; medications such as NSAIDs, antibiotics, and vaccines; and other problems such as inflammatory bowel disease, leukemia, and other cancers. The underlying mechanism is believed to involve the immune system. Diagnosis is based on symptoms and may be confirmed by tissue biopsy. There are two types erythema multiforme minor and erythema multiforme major.

Treatment is generally supportive or based on the underlying trigger. In those with HSV sunscreen or valacyclovir may be used. In more severe cases corticosteroids, dapsone, or cyclosporine may be used. Outcomes are generally good.

Erythema multiforme is uncommon. It most commonly occurs in the second and third decades of life. Males are more commonly affected than females. It was first described by von Hebra in 1860.