(Ch20) EM and SJS/TEN Flashcards
Rashes that increase in Spring and fall
EM & PR
Most common cause of EM?
infections 90%
MC HSV1>HS2
followed by mycoplasma pneumonia
what percentage of EM preceded by herpes labials?
50%
other name of EM minor caused by HSV?
Von Hebra’s
most common cause of EM major
Mycoplasma pneumonia
Mycoplasma pneumonia EM clinical features?
Severe Mucocutanous involvement with atypical papular targets
genetic associations with EM
HLA-DQw3
HLA-DRw53
HLA-Aw33
causes/triggers of EM?
- Infections 90%
viruses:
- HSV 1,2
- Parapox virus(orf)
-VZV, EBV
Bacteria:
-Mycoplasma pneumonia
-Chylamydia
- TB
fungal:
-Histoplasma capsulatum
- Drugs <10%
- physical triggers (trauma, UV and Clod ) kobener must be prior rash not after
- poison Ivy and vaccines
5.lupus & Bechet
which trigger or infection As/w Erythema nodosum
Histoplasma capsulatum
Drugs that can trigger EM?
SPAAN
Sulfa
Penicillin
Allopurinol
Anticonvulsants
NSAIDs
Pathogenesis of mycoplasma EM
molecular mimicry
which cell mediate HSV triggered EM
virus DNA transmitted by CD34+ to Th1 which releases IFN gamma
patients have normal immunity but may have difficulty clearing virus infected cells
Classic Primary lesion of EM
Typical targets
(3 zones)
1. center: dusky , vesicular or necrotic
2. pale oedematous rim
3. erythematous macule
Favours Face and distal extremities
Clinical lesions or features of EM
Typical targets
Atypical Papular targets (2 Zones)
+/- Mucosal involvement
what type of atypical targets present in EM vs SJS/TEN
Atypical Papular targets –> EM
Atypical Macular Targets–> SJS/TEN
Most common Location for EM rash
Dorsal hands and forearms
(UL>LL)
(distal > proximal)
face is a common location as well
Can EM progress to SJS?
No
clinical criteria to differentiate EM vs SJS/TEN
1.Type of lesions (typical and papular atypical targets)
- (Topography) Acrofacial distribution in EM
3.Abscence/presence of overt Mucosal involvement
- Path: ↓Eosin, ↓ epidermal necrosis
what are the systemic sx of EM
Fever and Arthralgia
EM Minor vs Major
both have targets (typical and papular atypical) and same distribution
Minor: no or mild mucosal involvement and no systemic sx
Major: Severe mucosal + systemic sx
oral variant of EM
MC in mid aged F
limited to oral cavity
MC mucosal location of EM
lips and buccal mucosa >ocular and genital
Earliest path sign of EM
Apoptosis of keratinocytes
Path of EM
basal Vacuolar interfacce dermatitis with apoptosis, spongosis and dermal inflammation and
absent or rare Eosin
normal SC. +/- vesicle
Path EM vs SJS/EM
EM: ↓Eosin, ↓ epidermal necrosis, ↑↑dermal inflammation
percentage of EM patient with HSV +ve PCR?
80%
Which part of the lesion to swab for HSV?
early papule or outer rim
how long does it take for EM to completely developed
72h
prognosis of EM?
Spontaneously resolves within 2 weeks without sequela
Severe mucosal may persist up to 6 weeks
ocular complications if not treated eye
Clinical course of EM?
abrupt onset 24h
fully developed 72h
resolves 2 weeks
Time limit to use antiviral ?
prior to sx
after sx ineffective
prophylactic Rx for EM?
Valtrex 1g/d for at least 6 months
Rx for EM
Mild Sx tx
Severe SCS/CsA/MMF/AZA
consider oral antihistamine for pruritus
antiseptic cream for rash
wound care
eye care
oral rinses/anethetics /antiseptics
EM vs Urticaria
EM:
1 -lesion’s centre damaged skin
2 -Fixed lesions
3 -fully developed 72h
4- no angiodema
Urticaria:
1 -centre normal skin
2 - transient lesions
3 - daily new lesions
4- +/-Angiodema
HSV recurrent EM frequency ?
2/year
RIME clinical features?
Clinical RIME:
1- Mucosal:
Severe mucositis
≥2 mucosal sites
2-cutanous:
-Vesiculobullous or atypical targets
- +/- sub corneal pustules
- <10% BSA