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 based on the level of exfoliation in the skin, with TEN having subepidermal cleavage and SSSS having intraepidermal cleavage at the granular layer. 1

Histopathological Differences

The definitive way to distinguish between these two potentially life-threatening conditions is through histopathological examination:

• TEN: Shows subepidermal vesicle or bulla formation with variable epidermal damage ranging from individual cell apoptosis to confluent epidermal necrosis 1
• SSSS: Shows intraepidermal cleavage specifically at the granular layer of the epidermis 1, 2

This histopathological distinction is crucial as it guides treatment decisions and affects prognosis.

Clinical Differences

While histopathology provides definitive diagnosis, several clinical features can help distinguish between these conditions:

Mucosal Involvement

• TEN: Significant mucosal involvement of eyes, mouth, nose, and genitalia is usually 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 (particularly sulfonamides, barbiturates, carbamazepine, and allopurinol) 3
• SSSS: Caused by phage group II Staphylococcus aureus infection producing exfoliative toxins 2, 4

Pathogenesis

• TEN: Direct cytotoxic effect on keratinocytes
• SSSS: Caused by circulating bacterial exotoxins (serine proteases) that specifically split desmoglein 1 2

Diagnostic Approach

When faced with a patient presenting with extensive skin exfoliation:

1. Perform skin biopsy: This is the gold standard for differentiation

   • Can be expedited by frozen section processing 2
   • Will show the level of cleavage (subepidermal in TEN vs. intraepidermal in SSSS)

2. Assess for mucosal involvement: Presence suggests TEN; absence suggests SSSS

3. Consider patient demographics: Children are more likely to have SSSS; adults more commonly have TEN

4. Review medication history: Recent introduction of high-risk medications suggests TEN

Clinical Implications

The distinction between these conditions is critical because:

• Treatment differs significantly: TEN may require specialized burn unit care and consideration of immunomodulatory therapy, while SSSS primarily requires antibiotics 5
• Prognosis varies dramatically: Mortality in SSSS is less than 10% in children but 40-63% in adults, while TEN has high mortality across age groups 2

Common Pitfalls

• Relying solely on clinical appearance without histopathological confirmation
• Failing to consider age as a factor (SSSS being more common in children)
• Not assessing for mucosal involvement, which is a key distinguishing feature
• Delaying diagnosis, which can increase mortality in both conditions

Early diagnosis through skin biopsy with identification of the cleavage plane remains the most reliable method for distinguishing between these two potentially fatal conditions.