Title: GZ / The Grenz Zone Season 2 / 22 SJS/TEN
Tags: GZ DermnetNZ

Q: [...] are rare but potentially fatal drug rashes that lead to keratinocyte death, full-thickness necrosis of the epidermis and severe desquamation of the skin and mucosal surfaces
A: Stevens-Johnson syndrome/Toxic Epidermal Necrolysis
Back Extra: SJS/TEN exist on a spectrum: SJS <10% body surface area, TEN > 30% body surface area

Q: The pathogenesis of SJS/TEN is thought to be due to a patient with [...] that is exposed to a [2 answers]
A: presdisposition; drug or a drug metabolite
Back Extra: This causes activation of FAS death receptor on keratinocytes leading to secretion of granulysin, granzyme B, and perforin from immune cells. This causes apoptosis of keratinocytes and eventual necrosis and sloughing of skin and mucous membranes

Q: The onset of SJS/TEN is typically [how many weeks] after drug exposure
A: 1-2 weeks

Q: Presdispositions for SJS/TEN include [fast or slow] acetylators of medications and certain [...] subtypes
A: slow; HLA
Back Extra: HLA- B-1502: Asians & East Indians exposed to carbamazepine
HLA- B-5801: Han Chinese exposed to allopurinol
HIV/AIDS patients

Common medications associated with SJS/TEN can be remembered by the pneumonic SATANN
S: Sulfonamides
A: Allopurinol
T: Tetracyclines
A: Anticonvulsants (e.g. phenytoin, carbamazepine, lamotrigine)
N: NSAIDs
N: Nevirapine
Back Extra: The MOST COMMON agent causing SJS/TEN is Bactrim (Sulfamethoxazole/Trimethoprim)

Q: Clinically, patients with SJS/TEN will have a prodrome of [...] 1-2 weeks after initial medication. 1-3 days later, [...] changes are noted. Skin findings typically start on the trunk as erythematous macules and targetoid with a dusky or purpuric center. Lesions will be tender to touch and quickly coalesce in hours to days. May progress to flaccid blisters and sheets of skin that start to desquamate.
A: fever/flu-like symptoms; mucocutaneous
Back Extra: Pearl: Nearly ALL patients with SJS/TEN will have mucosal involvement. ALWAYS look in the pt’s eyes, nose, mouth and genital mucosa if you are suspecting SJS/TEN!

Q: How do you distinguish SJS from Erythema Multiforme?
SJS: less likely to involve [...] extremities and has atypical macular target lesions that are NOT [...] or raised
A: distal; palpable
Back Extra: EM: Involves distal extremities and has palpable and raised targetoid lesions

Q: Name 3 differential diagnoses for a desquamating rash such as SJS/TEN? (TEMP)
[...], [...], and [...]
A: Toxic-shock syndrome; Erythema Multiforme Major; Pemphigus vulgaris
Back Extra: Other differentials include: Mycoplasma pneumonia-induced rash and mucositis (MIRM), DRESS (DIHS), purpura fulminans, Staph scalded skin syndrome, and acute graft-versus-host dz

Q: On histology, SJS/TEN presents with scattered apoptotic [specific cell type] and unimpressive perivascular lymphohistiocytic infiltrate with [specific cell type]. As lesions progress, there will be full thickness epidermal necrosis & development of subepidermal blisters.
A: keratinocytes; eosinophils
Back Extra: Arrow is pointing toward an apoptotic keratinocyte

Q: Prognosis of SJS/TEN can be calculated by the [...] score on arrival AND 48 hours later
A: SCORTEN
Back Extra: Remember TAMEBUG (each one counts as 1 point): Tachycardia >120, Age >40, Hx of malignancy, Epidermal loss >10%, Bicarb level >20 mEq/dL, Urea (BUN) >27 mg/dL, and Glucose >250 mg/dL

The SCORTEN score is calculated by using the pneumonic TAMEBUG
T: Tachycardia > 120 BPM
A: Age > 40
M: Hx of malignancy
E: Epidermal loss > 10%
B: Bicarb level > 20 mEq/dL
U: Urea (BUN) > 27 mg/dL
G: Glucose > 250 mg/dL
Back Extra: Each parameter counts as 1 point

Q: What is the most common complication of SJS/TEN that we try to prevent?
[...]
A: Ocular changes
Back Extra: Ocular changes include: chronic dry eyes, symblepharon ( see above; partial or complete adhesion of the inner eyelid to the conjunctiva of the eyeball), blindness
Other complications include:
Short term: Fluid loss leading to electrolyte abnormalities, hypovolemic shock, multiple organ dysfunction syndrome, bacterial infections → septic shock, pneumonia, ARDS
Long Term: Poor skin healing, dyspigmentation, scarring → hair loss & disfiguration (symblepharon, vaginal adhesions)

Q: Treatment of SJS/TEN includes stopping the [...] and [...]
A: offending medication; supportive/systemic treatment
Back Extra: Supportive care includes: wound care (petrolatum-impregnated gauze), infection prevention (antibiotic ointments), monitoring fluids and electrolytes, nutrition, Ophtho consult, OB-GYN consult (if applicable)
Systemic Tx includes: systemic steroids, IVIG, Cyclosporine, TNF-alpha inhibitors (infliximab, etanercept)