Scar

dermatological emergencies; DRESS; SJS; TEN;

SCAR is an acronym for "severe cutaneous adverse reactions". These include: erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis, DRESS ( drug reaction with eosinophilia and systemic symptoms ). These are often life-threatening "non-immunoglobulin E-mediated hypersensitivity reactions that differ from simple skin rashes in their immunological pathogenesis and involvement of internal organs" (Owen CE et al. 2021). SCARs are often associated with systemic (fever, organ failure, hematologic) involvement. SCARs are dermatologic emergencies.

The following clinical entities are the classic SCAR representatives:

• SJS (Stevens-Johnson syndrome): Skin involvement >10%; mortality 5-10%
• SJS/TEN-Overlap: skin involvement 10-30%;
• TEN: skin involvement >30%; mortality 20-40%
• DRESS: eosinophilia+organ involvement; mortality 5-10%
• AGEP: exanthema often >50% of KO; mortality about 1%

Typical triggering drugs are:

• Allopurinol
• Anticonvulsants (carbamazepine, lamotrigine, phenytoin)
• sulphonamides
• Antibiotics (beta-lactams, quinolones)
• NSAIDS (especially oxicam; acetaminophen)
• Nevirapine

SCAR is characterized by the following clinical features:

• temporal connection with medication (usually 1-8 weeks)
• severe, mostly generalized skin manifestation
• systemic inflammatory reactions
• relevant mortality
• immediate discontinuation of the triggering medication is essential for therapeutic purposes