What are the clinical signs of Stevens‑Johnson syndrome?

Clinical Signs of Stevens-Johnson Syndrome

Stevens-Johnson syndrome presents with a characteristic triad: a prodrome of fever and malaise, followed by painful skin lesions with atypical flat targets or purpuric macules, and severe erosive mucositis affecting multiple sites (eyes, mouth, genitalia). 1

Prodromal Phase (Precedes Skin Eruption)

• Fever, malaise, and upper respiratory tract symptoms typically occur several days before the rash appears 1
• Severe cutaneous pain is a critical early warning sign that may precede visible skin changes and should immediately alert clinicians to incipient epidermal necrolysis 1, 2
• Ocular inflammation may develop before any skin signs become apparent 1
• Symptoms typically begin 4-28 days after drug exposure 3, 4

Cutaneous Manifestations

Initial Lesion Characteristics

• Earliest lesions are atypical flat targets or purpuric macules with a dark-red center surrounded by a pink ring 1, 2
• Initial distribution: upper torso, proximal limbs, and face, then spreads to trunk and distal extremities 1, 2
• Palms and soles are frequently involved early in the disease course 1, 2

Progression Pattern

• Lesions expand and coalesce, reaching maximum extent 5-7 days after disease onset 1, 2
• Large areas of confluent erythema develop in severe cases 1
• Affected skin is exquisitely tender to touch 1
• Positive Nikolsky sign: gentle lateral pressure causes the epidermis to peel away from underlying dermis 1, 2
  • Caveat: This sign is helpful but not specific for SJS/TEN—it also occurs in pemphigus 1, 2

Advanced Skin Findings

• Flaccid blisters form as necrotic epidermis separates from dermis 1
• Sheet-like epidermal detachment exposes denuded dermis that exudes serum, bleeds readily, and is prone to secondary infection 1, 2

Mucosal Involvement (Usually an Early Feature)

• Erosive and hemorrhagic mucositis affecting eyes, mouth, nose, and genitalia is typically present early 1, 2
• Ocular signs: purulent keratoconjunctivitis, eyelid edema, and persistent inflammation 1, 5
• Oral mucositis: erythema, blistering, and painful erosions 5
• Genital involvement: pain and urinary retention 1
• Important distinction: In Mycoplasma-associated cases, mucosal involvement may predominate with minimal cutaneous lesions 1, 2

Respiratory Manifestations

• Cough, dyspnea, bronchial hypersecretion, and hemoptysis indicate respiratory tract involvement 1
• Dyspnea occurs in approximately 25% of patients 5
• Bronchial hypersecretion occurs in 70% of patients with early pulmonary manifestations 5

Gastrointestinal Signs

• Diarrhea and abdominal distension suggest bowel involvement 1

Classification by Extent of Epidermal Detachment

• SJS: <10% body surface area (BSA) detachment plus widespread purpuric macules or flat atypical targets 2, 6
• SJS-TEN overlap: 10-30% BSA detachment 2, 6
• TEN: >30% BSA detachment 2, 6

Critical Diagnostic Pitfalls to Avoid

• Do not dismiss early cutaneous pain—this symptom preceding visible skin changes is a red-flag for incipient necrolysis 1, 2
• Differentiate from erythema multiforme major: EMM has raised target lesions predominantly on limbs/extremities, whereas SJS has flat atypical targets more widely distributed 1, 2
• Differentiate from staphylococcal scalded skin syndrome (SSSS): SSSS lacks mucosal involvement and shows intraepidermal (not subepidermal) cleavage on biopsy 1
• Document both extent of erythema AND percentage of epidermal detachment, as detachable epidermis may initially appear as dusky erythema before frank blistering 2
• Consider infectious triggers (HSV, Mycoplasma, Chlamydia) in addition to drugs, especially in children with predominant mucositis and limited skin involvement 1