Hello! :)
TOXIC EPIDERMAL NECROLYSIS
-A severe form of adverse
cutaneous drug reaction
-Idiosyncratic reaction
-Immunologically Mediated
- Fever and mucocutaneous
lesions
-Epidermal sloughing
CLASSIFICATION
1. SJS= <10% BSA detachment
2. OVERLAPPING SJS/TEN= 10-30%
detachment
3. TEN = >30% detachment
EPIDEMIOLOGY
-Both are rare but occur as a
medical emergency.
-Incidence of SJS 1-7 Cases per
million.
-SJS > TEN by 3: 1
-TEN tend to be older
-Worldwide distribution
-HIV positive cases have
increased incidence.
ETIOLOGIES
-Drugs being the most common
cause
-Infection (viral e.g. HSV, bacterial,
fungi)
-Vaccination
-systemic disease (lupus)
-Physical agents (UV light,
radiation)
-Idiopathic 25%
Drugs that result in this are:-
-Antibiotics = sulfonamides
> penicillin > cephalosporin
-Anti-gout: allopurinol
-Anti-epileptics; carbamazepine,
Dilantin
-Anti-psychotics
-Analgesic including NSAIDS
RISK FACTORS:
GENETIC SUSCEPTIBILITY:-
-HLA-B*1502 associated with
greater risk with carbamazepine use in southeastern Asians.
-HLA-B*5801 confers risk with
allopurinol associated reactions.
-HLA-B*44 Caucasians
HIV:-
-Slow acetylators so results in
prolonged exposure to medications.
-Immune dysregulation
-Other infections
-40 Fold increased risk of
SJS/TEN with cotrimoxazole (Remember! It is used as a prophylactic drug in HIV
patients.)
CLINICAL PRESENTATION:-
-Drug exposure 1-3 weeks prior
to onset of symptoms
-PRODROME=fever, flu-like, 1-3
days
-symmetrical lesion
distribution
-starts on face and trunk
before spreading
-skin blistering with sloughing
for 2-3 days progressively then stabilizes
-Erythroderma
-Facial edema
-Skin pain- burning
-Palpable purpura
-Skin necrosis (Nikolsky sign)
-Blisters or epidermal
detachment
-SJS tragetoid, TEN target
lesions atypical
-Mucous membrane erosions or
crusting
-tongue swelling
-conjuctival irritation
-Dysuria
-GI bleed
-Pulmonary bleed
LABORATORY FINDINGS
-Anemia
-Lymphopenia
-Neutropenia (poor prognosis)
-Elevated transaminases
-Cultures, If infected
-Skin biopsy-Rule out other
conditions
-BUN/CR ratio
-Serum electrolytes
PATHOGENESIS
-not well understood
-Suspected immunologic
1. GRANULYSIN: Cytolytic
protein from cytotoxic T-cell and NK - cells
(Highly expressed in SJS /TEN
patients)
2. DEATH RECEPTOR CD95 (fas):
Elevated fas ligand leading to apoptosis
3. Perforin, TNF-alpha and
granzymes-B in higher concentration, associated with NON-APOPTOTIC death.
HISTOLOGY
-Early perivascular
inflammation of T-lymphocytes, primarily CD8
-Monocytes infiltration
-Lymphocytes surrounding basal
keratinocytes
-Subepidermal vesiculation
-Full thickness necrosis
-Increased adhesion molecules: VCAM,
ICAM
EVALUATION AND DIAGNOSIS
-Clinical diagnosis on the
basis on exclusion
-prior drug history or
illness+fever+skin lesions with sloughing
DIFFERENTIAL DIAGNOSIS
-toxic shock syndrome
(staphylococcus and streptococcus)
-Scalded skin syndrome
(staphylococcus)
-Phototoxic eruptions (Sun
exposure areas and known medications)
-Paraneoplastic pemphigus
(Lymphoma)
-Erythematous drug eruptions
(Lack mucosal involvement)
-Drug hypersensitivity syndrome
/DRESS/DIHS (eosinophilia)
-Acute generalized
exanthematous pustulosis (AGEP) (lack of pain and noted pustules)
-Toxic skin reaction (chemical
irritant)
-Toxic erythema (Intoxication)
-Kawasaki's (diagnostic
criteria)
EMM (ERYTHEMA MULTIFORME):
-targeted papules and plaques
-Acrally distributed
-Fever mild
-Significant skin detachment
uncommon
-Histology: inflammation
EMM>SJS
TREATMENT:-
-Immediate removal of possible
triggers (especially drugs with longer half-life)
-SUPPORTIVE CARE
- Wound care: burn unit
with improved outcomes
*avoid silver sulfadizine (Sulfonamide associated with SJS)
-Fluid and electrolyte
management (RL or NS)
-Pain control (Local
anesthetic cream)
-Temperature regulation:
caloric expenditure
-Monitor for infection:
pseudomonas
-Nutrition (High protein diet,
Banana) (I will discuss it in next post)
-Ocular care (Important)
You can also refer this link
That's all for today.
I will discuss the
case we have seen in the emergency ward on the same. And also the treatment
aspect.
-Upasana Y. :)
x
