Monday, July 24, 2017

Steven-Johnson syndrome (SJS) / Toxic epidermal necrolysis (TEN) -Part 1

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. :)




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