What is the distinction between toxic epidermal necrolysis (TEN) and staphylococcal scalded skin syndrome (SSSS) based on?

Distinction Between Toxic Epidermal Necrolysis and Staphylococcal Scalded Skin Syndrome

The key distinction between toxic epidermal necrolysis (TEN) and staphylococcal scalded skin syndrome (SSSS) is the level of exfoliation, with TEN having subepidermal cleavage and SSSS having intraepidermal cleavage at the granular layer.

Histopathological Differences

The definitive diagnostic distinction between these two potentially life-threatening conditions is based on skin biopsy findings that reveal the level of skin separation:

• TEN: Shows subepidermal vesicle or bulla formation with epidermal necrosis 1
• SSSS: Shows intraepidermal cleavage specifically at the granular layer 1, 2

This histopathological difference is critical because it guides treatment decisions and affects prognosis.

Clinical Distinguishing Features

While histopathology provides the definitive diagnosis, several clinical features can help differentiate these conditions:

Mucosal Involvement

• TEN: Significant mucosal involvement of eyes, mouth, nose, and genitalia is typically an early feature 1
• SSSS: Absence of mucosal involvement clinically distinguishes SSSS from TEN 1

Age Distribution

• TEN: Affects all age groups
• SSSS: More common in newborns and children than adults 2

Etiology

• TEN: Usually triggered by drugs (sulfonamides, anticonvulsants, allopurinol), rarely by infections 1, 3
• SSSS: Caused by phage group II Staphylococcus aureus infection producing exfoliative toxins 2, 4

Mortality

• TEN: Higher mortality rate (can exceed 40% in adults)
• SSSS: Lower mortality in children (<10%) but higher in adults (40-63%) 2

Diagnostic Approach

When faced with a patient presenting with extensive skin exfoliation:

1. Assess for mucosal involvement - presence strongly suggests TEN
2. Look for Nikolsky sign - positive in both conditions
3. Perform skin biopsy - the gold standard for differentiation
4. Consider frozen section processing for rapid diagnosis in emergent situations 2

Treatment Implications

The distinction is critical because treatment approaches differ significantly:

• TEN: Requires immediate withdrawal of offending drug, supportive care similar to burn management, and possibly immunomodulatory therapy
• SSSS: Requires prompt antibiotic therapy targeting S. aureus 2

Common Pitfalls

• Relying solely on clinical appearance without histopathological confirmation
• Failing to recognize that both conditions can present with Nikolsky sign and widespread exfoliation
• Not considering age as a factor (SSSS more common in children)
• Overlooking the importance of mucosal involvement as a key distinguishing feature

The correct answer is C. Level of exfoliation.