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Erythema multiforme

Last reviewed: 30 Sep 2024
Last updated: 18 Oct 2024

Summary

Definition

History and exam

Key diagnostic factors

  • target lesions of the extremities
  • previous episode of EM
  • mucosal erosions
Full details

Other diagnostic factors

  • targetoid lesions
  • rapid onset of lesions
  • self-limiting course
  • clustered vesicles on an erythematous base
  • rhonchi, rales, and/or wheezes
  • red tympanic membranes
Full details

Risk factors

  • prior episode of erythema multiforme
  • herpes simplex virus (HSV) infection
  • certain other infections
  • Mycoplasma pneumonia infection
  • lymphoma
  • Kawasaki disease
  • use of certain medications
  • vaccinations
  • tattoos
Full details

Diagnostic tests

1st tests to order

  • clinical diagnosis
Full details

Tests to consider

  • hematoxylin and eosin biopsy
  • immunofluorescence biopsy
  • CBC
  • serum electrolytes
  • herpes simplex virus (HSV) serology
  • rapid polymerase chain reaction (PCR)
  • cold-hemagglutination serology
  • M pneumoniae titers
  • CXR
  • autoantibody titers
Full details

Emerging tests

  • antidesmoplakin antibodies

Treatment algorithm

ACUTE

EM minor

EM major

ONGOING

recurrent EM

Contributors

Authors

Nathan W. Rojek, MD, FAAD

Assistant Professor

Director, Inpatient Dermatology

Department of Dermatology

University of California, Irvine

Irvine

CA

Disclosures

NWR declares that he has no competing interests.

Acknowledgements

Dr Nathan W. Rojek would like to gratefully acknowledge Dr Areta Kowal-Vern, Dr Jonathan Silverberg, and Dr Nanette Silverberg, the previous contributors to this topic.

Disclosures

AK-V, JS, and NS declare that they have no competing interests.

Peer reviewers

Cristine Radojicic, MD

Staff Physician

Cleveland Clinic

Cleveland

OH

Disclosures

CR declares that she has no competing interests.

Brian Swick, MD

Clinical Assistant Professor

University of Iowa College of Medicine

Iowa City

IA

Disclosures

BS declares that he has no competing interests.

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