A young child presents with blistering exfoliation over the face and neck. It started around the mouth. It has the appearance of impetigo, with the honey crusted lesions, but other areas have confluent denuding of the skin. You wonder whether this could be staphylococcal scalded skin syndrome (SSSS) or toxic epidermal necrolysis(TEN). How can these be differentiated at the bedside?
These diseases can be differentiated by the thickness of the skin. The toxin of SSSS cleaves at the stratum granulosum so the exfoliation is a very thin layer. TEN is full thickness. An online images search reveals how differently these diseases appear.
You look again at the child and see that the blistering reveals a very thin layer. That, in addition to the lack of mucus membrane involvement, and the confluent erythema of surrounding areas suggests that this is not TEN, but is staphylococcal. The toxin of impetigo and SSSS is the same. Given that this started around the mouth and spread from there, you diagnose severe impetigo.
Take Home Points
The toxin of SSSS (and impetigo) cleaves superficially, leaving thin blisters or flaking
TEN causes full thickness blistering