20- EM, SJS, TEN Flashcards
EM Epidemiology
male>female, young adult. not race differences.
EM - most commonly associated infectious agents
- HSV (type 1 and 2). 2. Mycoplasma pneumoniae, Histoplasma capsulatum (Fungal), and parapoxvirus.
*most cases in children and young adults are due to HSV type 1
Infections (approx. 90% of cases), other- drugs (unusual- NSAIDs, Sulfonamid, Anticonvulsants, antibiotics, e.g. aminopenicillins, Allopurinol); Exposures- poison ivy; Systemic disease (rare)- IBD, Lupus, Bechect.
EM- what % of Herpes labialis procced EM rash
Preceding herpes labialis is noted in ~50% of patients with EM. Most commonly, herpes labialis precedes target lesions of EM by 3–14 days. it may occur simultaneously or after as well.
Comparison of erythema multiforme minor and EM major
Mucosal involvement : EM minor - Absent or mild, EM major- Severe.
*The primary mucosal lesions of EM are vesiculobullous and rapidly develop into painful erosions that involve the buccal mucosa and lips
Systemic symptoms: EM minor- Absent, EM major- Usually present, with fever , Arthralgias.
Type of skin lesions: EM minor- * Typical targets
* ± Papular atypical targets
EM maor- as listed above, plus- Occasionally bullous lesions
SJS VS TEN BSA involvment
SJS<10% BSA
10%<SJS/TEN overlap<30%
TEN>30% BSA detachment
SJS, TEN Mususal involement
SJS- Severe
TEN- Severe, with involvement of respiratory and gastrointestinal mucosa
SJS, TEN systemic symptoms
Usually present
* Fever
* Lymphadenopathy
* Hepatitis
* Cytopenias
plus nephritis in TEN.
EM- topography
extremities and the face;
Target lesions favor the upper extremities, as does the entire eruption of EM- The dorsal aspects of the hands and the forearms are the most frequently involved sites, but the palms, neck, face and trunk are common locations as well
EM- natural history of the rash
almost all of the lesions appear within 24 hours and full development has occurred by 72 hours
Individual lesions remain fixed at the same site for 7 days or longer
For most individuals with EM, **the episode lasts 2 weeks **and heals without sequelae
Recurrence- ONE recurrence each spring, may occur. Most individuals with recurrent HSV-associated EM have one or two episodes a year, an exception being patients receiving immunosuppressive drugs (more events).
EM - histology
Histologic findings are characteristic, but not specific, and are most useful for excluding entities in the differential diagnosis such as lupus erythematosus (LE) and vasculitis
In EM, the keratinocyte is the target of the inflammatory insult, with apoptosis of individual keratinocytes being the earliest pathologic finding.
As the process evolves, mild spongiosis and focal vacuolar degeneration of basal keratinocytes are observed.
Superficial dermal edema and a perivascular infiltrate of lymphocytes with exocytosis into the epidermis are also seen
Compared to SJS, the dermal inflammation component is more prominent in EM and the epidermal “necrolysis” component is more discrete31.
Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN)
Epidemiology
Women>Men (1.5:1)
Risk factors:
-Slow acetylator genotypes
-Immunosuppression (Aids - 10k fold)
-Administration of radiotherapy and anticonvulsants
-HLA-B*15:02 – Asians, exposed to carbamazepine/lamotrigine/phenytoin.
-HLA-B*58:01– Chinese/allopurinol
HLA-A*31:01– Europeans/carbamazepine
Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN)
Mortality rates
SJS- 5%
TEN- 25% to 50% (average, 25–35%)
-Prompt withdrawal of the offending drug reduces the risk of death by 30% per day!
Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN)
Drugs associated with SJS/TEN
Allopurinol,
antibiotics
NSAIDs
Aromatic anticonvulsants.
Among the antibiotics, sulfonamides are the most strongly associated with SJS/TEN;
other antimicrobials include aminopenicillins, quinolones, cephalosporins, and tetracyclines as well as antiretrovirals.
*In general, the risk of developing SJS/TEN is reported to be highest during the initial week(s) of therapy.
*For the aromatic anticonvulsants, the risk is greatest during the first 2 months of treatment
Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN)
Systemic Clinical Features
fever, stinging eyes, and pain upon swallowing - precede cutaneous manifestations by 1 to 3 days
Additional systemic manifestations include lymphadenopathy, hepatitis, cytopenias, and cholestasis due to vanishing bile duct syndrome.
Skin lesions tend to appear first on the trunk, spreading to the neck, face, and proximal upper extremities.
*The distal portions of the arms as well as the legs are relatively spared; but the palms and soles can be an early site of involvement
Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN)
Mucosal involvment
Erythema and erosions of the buccal, ocular, and genital mucosae are present in** >90% of patients**
The epithelium of the respiratory tract is involved in 25% of patients with TEN, and gastrointestinal lesions (e.g. esophagitis, diarrhea) can also occur.
