How do you differentiate and treat a rash that could be either Steven Johnson syndrome (SJS) or contact dermatitis?

Differentiating and Treating Stevens-Johnson Syndrome versus Contact Dermatitis

Stevens-Johnson Syndrome (SJS) requires immediate hospitalization and discontinuation of suspected causative agents, while contact dermatitis can typically be managed with topical steroids and allergen avoidance.

Key Differentiating Features

Clinical Presentation

Feature	Stevens-Johnson Syndrome	Contact Dermatitis
Onset	Rapid, often with prodromal symptoms (fever, malaise)	Develops 24-96 hours after exposure
Distribution	Widespread, symmetrical	Localized to areas of contact
Mucosal Involvement	Prominent involvement of ≥2 mucosal surfaces (oral, ocular, genital)	Typically absent or limited
Skin Appearance	Blistering, epidermal detachment, Nikolsky sign positive	Erythema, vesicles, poorly defined borders
Pain	Severe cutaneous pain	Pruritus predominates
Systemic Symptoms	Fever, malaise, respiratory symptoms	Usually absent

High-Risk Features Requiring Urgent Action

Immediate hospitalization is necessary if any of these are present 1:

• Mucosal involvement in ≥2 sites
• Skin detachment >10% body surface area
• Vesicles, skin/mucous detachment, pustules, purpura
• Nikolsky sign (skin sloughing with lateral pressure)
• Severe pain rather than itching
• Systemic symptoms (fever, malaise)

Diagnostic Approach

1. Skin Biopsy: Essential for definitive diagnosis of SJS, showing full-thickness epidermal necrosis with extensive keratinocyte apoptosis 2

2. Laboratory Testing:

   • Complete blood count
   • Liver and kidney function tests
   • Consider bacterial cultures if infection suspected

3. Medication Review:

   • High-risk medications for SJS include: allopurinol, sulfonamides, aminopenicillins, cephalosporins, carbamazepine, phenytoin, NSAIDs 2

Treatment Algorithm

If SJS is Suspected:

1. Immediate Actions:

   • Discontinue all suspected causative medications
   • Urgent hospitalization, preferably to a specialized burn center or ICU 1
   • Consult dermatology immediately before starting any treatment 1

2. Supportive Care (cornerstone of management):

   • Fluid resuscitation
   • Temperature regulation
   • Pain management
   • Wound care
   • Nutritional support
   • Prevention of secondary infections 1

3. Specific Interventions:

   • Consider systemic corticosteroids early in disease course 1
   • For severe cases, consider IVIG (intravenous immunoglobulin) 3
   • Ophthalmology consultation for ocular involvement 1

If Contact Dermatitis is Suspected:

1. Mild to Moderate (Grade 1-2):

   • Identify and remove the allergen
   • Topical corticosteroids appropriate for affected area (avoid high-potency steroids on face, groin, axillae) 4
   • Oral antihistamines for pruritus
   • Cool compresses

2. Severe (Grade 3):

   • Short course of systemic corticosteroids (prednisone) 5
   • Dermatology consultation
   • Consider patch testing after resolution to identify specific allergen

Pitfalls and Caveats

1. Delayed Diagnosis: SJS can be mistaken for other conditions initially, delaying critical intervention. When in doubt, consult dermatology urgently.

2. Inappropriate Steroid Use: Starting treatment with steroids prior to ophthalmologic examination in cases with eye involvement may worsen conditions due to infection or mask accurate diagnosis 1.

3. Incomplete Medication Discontinuation: Failure to immediately stop all potential causative medications can lead to disease progression in SJS.

4. Misdiagnosis: Other conditions that can mimic SJS include:

   • Staphylococcal scalded skin syndrome
   • Erythema multiforme
   • Bullous pemphigoid
   • Drug-induced linear IgA dermatosis 2

5. Underestimating Severity: What appears initially as contact dermatitis may evolve into SJS. Progressive symptoms warrant reassessment.

Remember that SJS is a medical emergency with mortality rates of 1-5%, while TEN (the more severe form with >30% skin detachment) has mortality rates of 25-35% 2. Early recognition and appropriate management are critical for improving outcomes.