Stevens-Johnson Flashcards
Name the disease: Target like lesions with less than 10% of the body affected, commonly triggered by herpes simplex virus or mycoplasma
Erythema Multiforme
What differentiates SJS from eryhtoderma and eryhtematous drug eruptions?
SJS has mucosal involvment, while eryhtoderma and drug eruptions do not
What is phototoxic eruption?
Reaction to recent sun exposure, drug induced
What are two important things about SJS?
They have sever mucocutaneous reactions
-triggered by medications (usually 4-8 weeks after starting)
What determines SJS, vs. SJS/TEN, vs TEN?
Body surface affected.
less than 10% is SJS
10-30% is SJS/TEN
greater than 30% is TEN
What is prevalence of SJS to TEN?
SJS to TEN is 3:1, with 2-7 cases per million people per year
What is prevelance in HIV pts?
HIV patients are at 100 fold increase of SJS or TEN
What is mortalits for SJS and TEN?
SJS is 10%
TEN is 30%
What is most common etiology of SJS/TEN?
almost 75% is drug related
- happens 4-8 weeks after starting medication
- common in allopurinol (treament of gout), anti-seizure (phenobarbital and carbamazepine)
- antibacterial sulfonamides (like Bactrim)
- lamotrigine
- nevirapine
What are predisposing factors to SJS/TEN?
- HIV
- Genetics
- Underlying imunnologic disease
- medications
- infections like mycoplasma penumonia
What are the genetics in SJS/TEN and what is important about them?
HLA-B*1501 and HLA-B*5801
- must genetically test patients before starting anti-seizure medications
- also more common in asians.
What are some genetic polymorphisms with SJS/TEN?
CYP2C19- coding for cytochrome p450, leads to reduced clearence of medications in the liver and increased risk of severe cutaneous reactions
IL-4 Receptor gene
Prostaglandin E receptor 3 gene
-using 2+ durgs with the same metabolic pathway will increase risk of SJS/TEN
What is the underlying pathogenesis is SJS/TEN?
killing of keratinocyts by massive apoptosis, usually through CTLs, Fas-FasL, and NK cells
What is Granzyme B?
A cytolytic protein secreted by CTLs and NK cells
- induces apoptosis and a hihg level of ganzyme B is associated with disease
- perforin creates hole for entry.
- Granzyme B celaves Bid, recruits Bax and BAk, increases mitochondria permeability and release of cytochrome C
What is Granulysin?
Antimicrobial and cyottoxic chemical expressed by CTL and BK cells, causes the release of caspase 3 and keratinocyte death.
-found in blister fluid of lesions