Symptoms may include fever, swelling, and complaint of excessive pain. The initial skin changes are similar to cellulitis or abscess, thus making the diagnosis at early stages difficult. Hardening of the skin and soft tissue and swelling beyond the area of skin changes are commonly present in those with early necrotizing changes. The redness and swelling usually blend into surrounding normal tissues. The overlying skin may appear shiny and tense. Other signs which are more suggestive of necrotizing changes (but present in later stages in 7 to 44% of the cases) are: formation of bullae, bleeding into the skin which is present before skin necrosis (skin turning from red to purple and black due to thrombosis of blood vessels), presence of gas in tissues, and reduced or absent sensation over the skin (due to the necrosis of the underlying nerves). Rapid progression to shock despite antibiotic therapy is another indication of necrotizing fasciitis. Necrotizing changes affecting the groin are known as Fournier gangrene.
However, those who are immunocompromised (have cancer, use corticosteroid, on radiotherapy, chemotherapy, HIV/AIDS, or prior organ or bone marrow transplantation) may not show normal symptoms. Immunocompromised persons also have twice the risk of death from necrotizing infections, so higher suspicion should be maintained in this group.
