Erythema multiforme

Last reviewed: 27 Apr 2022
Last updated: 28 Jan 2021

Summary

Definition

History and exam

Key diagnostic factors

  • target lesions of the extremities
  • recurrent disease
  • mucosal erosions
More key diagnostic factors

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
  • hepatomegaly
Other diagnostic factors

Risk factors

  • prior occurrence
  • herpes simplex virus (HSV) infection
  • cytomegalovirus (CMV) infection
  • Epstein-Barr virus (EBV) infection
  • Mycoplasma pneumonia
  • hepatitis B virus infection
  • histoplasmosis
  • HIV infection
  • lymphoma
  • orf virus infection
  • medications
  • tattoos
  • hepatitis B vaccine
  • syphilis
More risk factors

Diagnostic investigations

1st investigations to order

  • CBC
  • serum electrolytes
  • herpes simplex virus (HSV) serology
  • rapid polymerase chain reaction (PCR)
  • cold-hemagglutination serology
  • M pneumoniae titers
  • CXR
  • autoantibody titers
More 1st investigations to order

Investigations to consider

  • hematoxylin and eosin biopsy
  • immunofluorescence biopsy
  • hepatitis B virus (HBV) serology
  • LFTs
More investigations to consider

Emerging tests

  • antidesmoplakin antibodies

Treatment algorithm

ACUTE

EM minor

EM major

ONGOING

recurrent EM

Contributors

Authors

Areta Kowal-Vern, MD

Adjunct Research Faculty

Arizona Burn Center

Maricopa Integrated Health Systems

Phoenix

AZ

Disclosures

AK-V declares that she has no competing interests.

Acknowledgements

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

Disclosures

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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