Last reviewed: 10 Nov 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.
Differentials
- Urticaria
- Polymorphous light eruption (PMLE)
- Subacute cutaneous lupus erythematosus
More DifferentialsGuidelines
- Erythema multiforme
- Diagnosis and treatment of adults with community-acquired pneumonia
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