Pathophysiology
- The overlying skin may often appear unaffected initially due to the deep nature of the infection. This is unlike cellulitis where the infection begins at the junction between the dermis and superficial fascia and so appears red at the skin surface. In necrotising fasciitis, the infection starts at the level of subcutaneous fat and deep fascia, presenting a diagnostic challenge, as the extent of the infection is not clear from the surface10.
- Type 2 NF is particularly associated with an exotoxin-driven toxic shock syndrome. This results from massive T-cell proliferation and cytokine release, and produces the typical clinical picture of NF, with profound hypotension and rapidly progressive multiorgan dysfunction leading to significant mortality11.