Toxic Epidermal Necrolysis

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Contents 1 Etiology 2 Epidemiology 3 Pathology 4 Genetics 5 Clinical-manifestations 6 Laboratory 7 Complications 8 Differential-diagnosis 9 Management 10 More General Terms 11 Additional Terms 12 References

Etiology

• allergic reaction, almost always to a drug
• offending pharmaceutical agents

• antibiotics: nalidixic acid, penicillins, sulfonamides
• anticonvulsants: phenytoin, carbamazepine, barbiturates
• NSAIDs: phenylbutazone
• other: allopurinol, bromides, iodides, chlormezanone
• see pharmaceutical agents causing SCARs

• less common causes:

• radiation, malignancy, vaccination, graft vs. host

Epidemiology

• all age groups affected; uncommon in children
• female predominance (1.5-2:1)
• high incidence in HIV+ patients (1/1000/year)

Pathology

• acute epidermal necrosis

Genetics

• drug-induced TEN ( carbamazepine, phenytoin) linked to HLA-B*1502 in Han Chines (Asians, South Asian Indians)

Clinical-manifestations

• prodrome of malaise, anorexia, arthralgias, fever & upper respiratory tract infection 1-3 days before appearance of skin lesions
• skin & mucous membrane manifestations

• initially, warm, diffuse erythema, spreading from face & genitalia
• later, generalized tender erythema, often with bullae formation
• Nikolsky's sign
• early blistering, eroding oral- labial lesions (90%)
• sloughing & necrosis of entire epidermis
• purulent conjunctivitis (75%)

Laboratory

• blood cultures
• complete blood count ( CBC)

• anemia
• leukocytosis
• eosinophilia

• serum electrolytes, serum urea nitrogen, serum creatinine
• liver function tests
• erythrocyte sedimentation rate may be elevated
• urinalysis

• proteinuria
• hematuria

• skin biopsy if diagnosis uncertain

Complications

• death generally occurs from sepsis
• GI hemorrhage
• pulmonary embolism

Differential-diagnosis

• Stevens-Johnson syndrome ( SJS)

• TEN is a severe form of SJS
• in SJS, skin detachment effects < 10% of body area
• in TEN, skin detachment effects > 30% of body area

Management

• treat like a burn
• hospitalize in intensive care or burn unit
• rehydrate & correct electrolyte imbalances
• aggressive treatment of suspected infections

• Staphylococcus
• Pseudomonas
• no role for prophylactic antibiotics [3]

• use of steroids is controversial

• Prognosis:

• overall mortality is 30% (10%-70%)
• poorer prognosis with advanced age, extensive surface area involved & azotemia
• see SCORTEN severity index score

More General Terms

• skin disease (dermatologic disorder, dermatopathy, dermatosis)
• sign/symptom

Additional Terms

• burn
• Nikolsky's sign
• pharmaceutical agents causing severe cutaneous adverse reactions (SCARs)
• SCORTEN severity index score
• Stevens-Johnson syndrome (SJS)

References

1. Harrison's Principles of Internal Medicine, 13th ed. Companion Handbook, Isselbacher et al (eds), McGraw-Hill Inc. NY, 1995, pg 829-39
2. H. Quinny Cheng, USSF Fresno lecture, Oct 21, 1998
3. Medical Knowledge Self Assessment Program (MKSAP) 11, 15, American College of Physicians, Philadelphia 1998, 2009
4. Harrison's Principles of Internal Medicine, 14th ed. Fauci et al (eds), McGraw-Hill Inc. NY, 1998, pg 94

toxic (bullous) epidermal necrolysis (Lyell syndrome, TEN)