Clinical Pearls: Erythema Multiforme, Stevens-Johnson, Toxic Epidermal Necrolysis

Erythema Multiforme (EM), Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) exist on a spectrum but vary considerably with regard to presentation and underlying etiologies. Here are some clinical pearls to help conceptualize these fascinated pathologies.

EM SJS  TEN
Morphology Typical three-zoned target Atypical targets and confluent erythema with sloughing Extensive, confluent erythema with sloughing
Distribution Favors extremities Trunk, extremities

Up to 10% BSA involvementa

Trunk, extremities

At least 30% BSA involvementa

Mucosal disease (oral, eye, genitourinary) One or two sites Two or more sites Two or more sites
Constitutional symptoms + ++/+++ +++
Caused by infection (%) (herpes simplex orMycoplasma pneumoniae) 30-80 22 6
Caused by drugs implicated in (%) Up to 50 74 94
Mortality (%) 0 5-13 25-39