What are the differences in diagnosis and treatment between lichenoid drug rash, Steven Johnson syndrome, lichen planus, and psoriasis?

Differences Between Lichenoid Drug Rash, Stevens-Johnson Syndrome, Lichen Planus, and Psoriasis

The most critical difference between these conditions is that Stevens-Johnson Syndrome (SJS) is a medical emergency with potential mortality of up to 30% for its severe form (TEN), while lichenoid drug rash, lichen planus, and psoriasis are generally not life-threatening conditions. 1

Clinical Presentation

Stevens-Johnson Syndrome (SJS)

• Onset: Prodrome of fever, malaise, upper respiratory symptoms preceding eruption by days 1
• Skin: Atypical targets/purpuric macules progressing to widespread epidermal detachment and flaccid blisters 1
• Mucosa: Severe multi-site mucositis (ocular, oral, genital) is characteristic 1
• Nikolsky sign: Positive (epidermis slides over dermis with gentle pressure) 1
• Pain: Cutaneous pain is a prominent early feature 1
• Distribution: Initially upper torso, proximal limbs, face; spreads to trunk and distal limbs 1

Lichenoid Drug Rash

• Onset: Can take several months to develop after drug exposure 2
• Skin: Erythematous papules or plaques resembling lichen planus 1
• Mucosa: Can involve mucosal areas with painful ulcerations 1
• Distribution: More widespread and asymmetric than idiopathic lichen planus 3
• Common triggers: Beta-blockers, methyldopa, penicillamine, quinidine, quinine 4

Lichen Planus

• Onset: Gradual development without prodromal symptoms
• Skin: Shiny, flat-topped, violaceous papules with white reticulated lines (Wickham's striae) 5
• Mucosa: Can involve oral mucosa with white lacy pattern
• Distribution: Typically affects wrists, ankles, lower back, and genitalia; often symmetric 5
• Pruritus: Often intensely itchy

Psoriasis

• Skin: Well-delimited erythematous and scaly plaques 1
• Mucosa: Can involve mucous areas and nails (subungual hyperkeratosis) 1
• Distribution: Typically affects extensor surfaces (elbows, knees), scalp, and intergluteal cleft
• Characteristic: Silvery scale that bleeds when removed (Auspitz sign)
• Prevalence: Affects approximately 3% of the population 1

Diagnostic Approach

Stevens-Johnson Syndrome

• Biopsy: Shows multiple apoptotic keratinocytes throughout full epidermis thickness, subepidermal split forming bulla, perivascular lymphocytic infiltrate 1
• Lab tests: Complete blood count, renal/liver function tests, coagulation studies, mycoplasma serology 1
• Imaging: Chest X-ray to evaluate for pulmonary involvement 1
• Severity assessment: SCORTEN prognostic scoring system to predict mortality 1

Lichenoid Drug Rash

• Biopsy: Similar to lichen planus but with more eosinophils and parakeratosis 2
• Key diagnostic feature: Chronologic relationship to drug exposure and improvement after drug discontinuation 4
• Challenge: May take months to develop, making identification of culprit drug difficult 2

Lichen Planus

• Biopsy: Dense band-like lymphocytic infiltrate at dermal-epidermal junction, saw-toothed acanthosis, hyperkeratosis, hypergranulosis 1
• Direct immunofluorescence: May show deposits of IgM at dermal-epidermal junction

Psoriasis

• Biopsy: Acanthosis with elongated rete ridges, parakeratosis, neutrophilic microabscesses, dilated capillaries in dermal papillae
• Clinical diagnosis: Often made based on characteristic appearance and distribution

Treatment Approaches

Stevens-Johnson Syndrome

• Immediate action: Discontinue potential culprit drug immediately 1
• Hospitalization: Transfer to specialized unit (burn/ICU) 1
• Supportive care: IV fluid resuscitation, wound care, pain management, nutritional support 1
• Monitoring: Fluid/electrolyte balance, prevention of infection, respiratory support if needed 1
• Specific therapies: Controversial; some evidence for early high-dose corticosteroids, IVIG, or cyclosporine in selected cases 1
• Mortality risk: 1-5% for SJS, 25-35% for TEN 6

Lichenoid Drug Rash

• Primary treatment: Discontinuation of the offending medication 5
• Symptomatic relief: Topical corticosteroids for pruritus and inflammation
• Resolution time: May take weeks to months after drug discontinuation
• Caution: Paradoxically, antihistamines and corticosteroids themselves can cause lichenoid reactions in rare cases 3

Lichen Planus

• Topical therapy: Potent topical corticosteroids for localized disease
• Systemic therapy: For widespread/severe disease - oral corticosteroids, acitretin, cyclosporine
• Phototherapy: UVB or PUVA for resistant cases
• Natural history: Often self-limiting over 1-2 years, but can be chronic

Psoriasis

• Topical therapy: Corticosteroids, vitamin D analogs, retinoids, calcineurin inhibitors
• Phototherapy: UVB or PUVA for moderate-severe disease
• Systemic therapy: Methotrexate, cyclosporine, acitretin, apremilast
• Biologics: TNF inhibitors, IL-17 inhibitors, IL-23 inhibitors for moderate-severe disease
• Natural history: Chronic condition with remissions and exacerbations

Key Distinguishing Features

1. Mucosal involvement:

   • SJS: Severe multi-site mucositis is characteristic and often precedes skin lesions 1
   • Lichenoid drug rash: Variable mucosal involvement
   • Lichen planus: Oral involvement common (30-70%) with white lacy pattern
   • Psoriasis: Mucosal involvement less common

2. Epidermal detachment:

   • SJS: Significant epidermal detachment (10-30% BSA in SJS/TEN overlap, >30% in TEN) 1
   • Lichenoid drug rash, lichen planus, psoriasis: No significant epidermal detachment

3. Time course:

   • SJS: Rapid onset (days) with prodromal symptoms 1
   • Lichenoid drug rash: Delayed onset (weeks to months) after drug exposure 2
   • Lichen planus: Gradual onset, often chronic course
   • Psoriasis: Variable onset, typically chronic with remissions and exacerbations

4. Mortality risk:

   • SJS: Significant mortality risk (1-5% for SJS, 25-35% for TEN) 6
   • Lichenoid drug rash, lichen planus, psoriasis: Rarely life-threatening

Management Pitfalls to Avoid

1. Delayed recognition of SJS: Failure to recognize early signs of SJS can lead to increased mortality. Cutaneous pain out of proportion to visible skin changes is an early warning sign 1

2. Continued use of culprit medication: Particularly important in SJS and lichenoid drug rash where continued exposure worsens the condition 1

3. Inadequate supportive care in SJS: SJS requires specialized care similar to burn patients with attention to fluid balance, wound care, and prevention of infection 1

4. Misdiagnosis of lichenoid drug rash as idiopathic lichen planus: Leading to continued drug exposure and persistent/worsening disease 4

5. Overlooking potential drug causes: Many drugs can cause lichenoid eruptions, including some that may not be commonly recognized (e.g., NSAIDs, ACE inhibitors) 4

6. Underestimating psychological impact: All these conditions, especially when chronic or affecting visible areas, can have significant psychological effects requiring appropriate support

By understanding these key differences, clinicians can more accurately diagnose and appropriately manage these dermatological conditions, with particular attention to identifying the potentially life-threatening SJS/TEN spectrum disorders that require immediate intervention.