Erythema multiforme

Erythema multiforme, Steven Johnson Syndrome/Toxic Epidermal Necrosis

Updated: 02/24/2021

© Jun Wang, MD, PhD


General features
  • Uncommon, acute process
  • May be self limited in minor forms, or life threatening
  • Risk factors: Immune abnormalities, including HIV infection, corticosteroid exposure, bone marrow transplant, autoimmune disorders, and inflammatory bowel disease
  • Likely EM and SJS/TEN are two different diseases 
  • EM: slightly more common in young male
  • SJS/TEN: more common in female
  • Diagnosed based on clinical presentations
Pathogenesis
  • Type IV hypersensitivity reaction associated with infections, drugs, carcinoma / lymphoma, or collagen vascular disorders
  • Immune complex mediated reaction
  • Erythema multiforme minor and major: more commonly associated with viral infections
  • SJS/TEN: more commonly associated with drug reaction
Classifications
  • Erythema multiforme minor: Typical targets or raised, edematous papules distributed acrally
  • Erythema multiforme major: Typical targets or raised, edematous papules distributed acrally with involvement of one or more mucous membranes; epidermal detachment involves less than 10% of total body surface area (TBSA).
  • SJS/TEN: Widespread blisters predominant on the trunk and face, presenting with erythematous macules and one or more mucous membrane erosions
Steven-Johnson syndrome: < 10% Epidermal detachment
Toxic epidermal necrolysis: > 30% Epidermal detachment
Overlapping SJS/TEN: 10-30% epidermal detachment

Clinical features
  • Affects skin (distal extremities, palms, soles) and mucous membranes
  • Variable (multiform) lesions – papules, macules, vesicles, bullae, target
  • Either localized (erythema multiforme minor) to systemic, life-threatening (Stevens-Johnson syndrome/Toxic epidermal necrolysis)
  • Starting from extremities symmetrically with centripetal spreading
  • Pruritus usually absent
  • Target lesion:
Central dark area or a blister surrounded by
A pale edematous zone surrounded by
A peripheral rim of erythema

Pathological findings
Stevens-Johnson syndrome and toxic epidermal necrolysis
  • May be life threatening
  • Wide spread erythematous macules and targetoid lesions
  • Mucous membranes commonly involved
  • Likely immune-complex mediated
  • Full thickness epidermal necrosis with minimal dermal inflammation
  • Diagnosis
    • History of drug exposure or febrile illness
    • Prodrome of acute onset febrile illness and malaise
    • Rapidly progressing painful rash
    • Erythematous macules, targetoid lesions, diffuse erythema to blisters
    • Mucosa involvement
    • Necrosis and sloughing of epidermis
  • Treated symptomatically
  • Pay special attention to airway and hemodynamic stability, fluid status, wound/burn care, and pain control
  • Extensive debridement of nonviable epidermis followed by immediate cover with biologic dressings
Management
  • Symptomatic treatment, including oral antihistamine, local skin care, etc
  • Transfer to and care in a burn unit for patients with Stenvens-Johnson Syndrome and toxic epidermal necrolysis
  • Identify the cause if possible
Prognosis
  • Most are self-limited
  • Mortality proportional to the total body surface area of sloughed epithelium
  • Skin lesion usually heal with hyper and/or hypopigmentation
  • Scarring rare unless infected secondarily


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