EM, SJS, TEN Flashcards
Most common cause of EM?
HSV (HSV1 more common)
What seperates EM minor and major?
In EM minor the target lesions are associated with minimal mucosal involvement and NO systemic symptoms
What is the most common cause of erythema multiforme (EM) major?
Mycoplasma Pneumoniae
It often has severe mucous membrane involvement (simulates SJS).
What is the major driver of prognosis in SJS and TEN
Speed at which culprit drug is identified and withdrawn.
What is the major mediator of apoptosis in SJS and TEN
Granulysin –> secreted in cytotoxic granules of CD8+ T-cells/NK-cells, directly damages keratinocytes.
What is the difference in distribution between EM and TEN/SJS?
Distal extremities are relatively spared in SJS/TEN and lesions tend to be more proximal. This is reversed in EM
What is the SCORTEN system?
For gauging prognosis in SJS/TEN: has to be done on day 1 and day 3 Tachycardia (>120bpm) Age (>40) Malignancy Epidermal loss >10% Bicarbonate Urea (>17) Glucose (>120)
What is the most important indicator of mortality within the SCORTEN scoring?
Serum bicarbonate (<20mmol/L)
Does bactrim and furosemide cross-react for SJS TEN?
NO! sulfa abx do not cross-react with other sulfa medications like furosimide
Epidemiology for EM?
Young adults; slight male predominance, 90% of cases d/t infection (HSV 1>2), drugs (<10%, NSAIDS, abx, sulfa, antiepileptics, TNF-a inhibitors), systemic dz, physical triggers.
What Infections can cause EM?
HSV, Mycoplasma pneuoniae (mucosal involvement), histoplasma capsulatum, parapoxvirus (orf)
Describe classic target lesions in EM?
<3mm, regular round shape, well-defined border, 3 distinct zones: 2 concentric rings of color change surrounding central circular zone that has evidence of damage to the epidermis (vesicles, blister, dusky appearance)
Usually palpable!
Describe atypical target lesions?
Round, edematous, macular, only 2 zones or poorly defined border
Macules are key, classic lesions tend to be palpable
Difference between SJS/TEN and EM lesions?
In SJS the lesions tend to be macular, non-palpable, non-elevated atypical targets. They also tend to be more centrally distributed with more involvement of the mucous membranes
Most common locations for EM?
Distal extremities (UE>LE), palms, neck, face and trunk are commonly involved as well.
Definition of EM minor?
Target lesions w/ minimal mucosal involvement and NO systemic sx’s.
Definition of EM major?
Mycoplasma pneumonia is most common, target lesions w/ severe mucosal involvement and systemic sx. Mucosal sx’s are severe and rapidly develop into painful erosions that involve buccal mucosa and lips. -Systemic sx’s are usually fever, asthenia, arthralgias, joint swelling, pulmonary
What cause of EM also tends to have concomitant EN?
Histoplasma capsulatum
Timeline of EM?
Almost all lesions appear within 24 hours, full development by 72 hours, pruritus and burning, individual lesions remain fixed at the same site for 7 days or longer.
Episode lasts 2 weeks and heals without sequelae in post pts.
What is the earliest histologic sign of EM?
Apoptosis of individual keratinocytes
Differential diagnosis for EM?
Giant urticaria, fixed frug eruptions (neuts, pigment incontinence), subcutaneous LE, Kawasaki disease, erythema annulare centrifugum, vasculitis
Difference between urticaria and EM?
For urticaria: central zone is clear, lesions are transient, new lesions appear daily, associated w/ swelling of face hands or feet.
Treatment for EM minor compared to major?
Minor: oral antihistamines for 3-4 days, topical therapy Major: pred 0.5-1mg/kg/day or pulsed methylprednisolone (20mg/kg/day for 3 days). May be a/w ocular complications.
Etiology of SJS/TEN?
Nearly always drug-related
