Stevens–johnson Syndrome

Basics

Stevens–Johnson syndrome (SJS) is a disease that affects the skin and mucous membranes, causing necrosis and detachment of the epidermal layers
SJS is either drug induced, related to infection, or idiopathic
SJS and toxic epidermal necrolysis (TEN) are considered a disease continuum and differ only in the amount of body surface involvement:
- SJS: <10% of body surface area (BSA)
- SJS–TEN overlap syndrome: 10–30% of BSA
- TEN: >30% of BSA, can affect up to 100% BSA
- SJS and TEN are different from erythema multiforme
SJS characteristics:
- Blistering of <10% of the BSA
- 95% of patients have mucous membrane lesions:
  - Usually at 2 or more sites
  - Ocular, oral, genital
- 85% have conjunctival lesions
- Lesions often involving face, neck, and central trunk regions become confluent over hours to days
Age of onset is any age, but most common in adults older than 40
More common in women, female to male ratio of 2:1

The most common causes include medications and infections:
- The pathology of skin damage is not completely understood
- Damage to the skin is thought to be mediated by a cell mediated cytotoxic immune reaction aimed at destruction of keratinocytes expressing (drug-related) antigens
  - Leads to massive apoptosis
- Medications cause the vast majority of SJS, usually in the first 8 wk of treatment
Causative medications:
- Antibiotics (penicillin, sulfonamides, others)
- Anticonvulsants (phenytoin, phenobarbital, carbamazepine, lamotrigine, others)
- NSAIDs
- Antineoplastics (thalidomide, tamoxifen, others)
- HIV drugs (nevirapine)
- Allopurinol
Infections:
- Mycoplasma pneumoniae is the second most common cause of SJS
- Herpes simplex
- Viral infections

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