[Necrotizing fasciitis, part 2 : Differential diagnoses of necrotizing fasciitis].

Necrotizing fasciitis (NF) is known to be a potentially life-threatening bacterial infection of the deep fascias showing a tendency to rapid spread. For certain localizations (e.g., the scrotum or labia) of this disease, specific entities have been defined (e.g., Fournier's gangrene). Cellulitis (or phlegmon) represents the most important differential diagnosis of NF. Moreover, septic soft tissue infections with fascial involvement together with eosinophilic and paraneoplastic fasciitis can be diagnostically challenging. The large group of autoimmunologically mediated inflammatory systemic disorders (such as lupus myofasciitis) at least shares some radiological similarities, although both its bilateral and partially symmetrical involvement pattern as well as the overall clinical constellation would argue against it.