Last reviewed: 30 Oct 2020
Last updated: 11 Dec 2018



History and exam

Key diagnostic factors

  • target lesions of the extremities
  • recurrent disease
  • mucosal erosions

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

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

Diagnostic investigations

1st investigations to order

  • CBC
  • serum electrolytes
  • herpes simplex virus (HSV) serology
  • rapid PCR
  • cold-hemagglutination serology
  • M pneumoniae titers
  • CXR
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
More emerging tests

Treatment algorithm


Adjunct Research Faculty

Arizona Burn Center

Maricopa Integrated Health Systems




AK-V declares that she has no competing interests.

Dr Areta Kowal-Vern would like to gratefully acknowledge Dr Jonathan Silverberg and Dr Nanette Silverberg, the previous contributors to this topic. JS and NS declare that they have no competing interests.

Peer reviewersVIEW ALL

Staff Physician

Cleveland Clinic




CR declares that she has no competing interests.

Clinical Assistant Professor

University of Iowa College of Medicine

Iowa City



BS declares that he has no competing interests.

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