SKIN AND SOFT TISSUE INFECTIONS: GENERAL APPROACH AND DIFFERENTIAL DIAGNOSIS

Since spread to adjacent tissues and progression to sepsis and death can occur in as little as a few hours, a high index of suspicion is essential for necrotizing soft tissue infections. Delays in diagnosis and surgical debridement have been shown to increase mortality. Although they may have different presentations, all types of necrotizing soft tissue infections have similar management principles, and any suspected case requires emergency surgical exploration and the initiation of adjunct treatment measures.

It can be difficult to differentiate necrotizing soft tissue infections from non-necrotizing skin infections. Because the deeper necrotizing infections do not initially affect the skin, symptoms and signs out of proportion to local findings are an early characteristic. Crepitus, severe pain, and systemic toxicity are uncommon in cellulitis, and these findings should always raise suspicion for a deeper process. Erysipelas usually manifests with well-demarcated borders, lymphangitis, lymphadenopathy, and minimal swelling, all of which are uncharacteristic of necrotizing fasciitis. Other clues that suggest necrotizing fasciitis include firmness of the subcutaneous tissues beyond the area of skin involvement, cutaneous anesthesia, and cellulitis that does not respond to antibiotics in 24 to 48 hours.

Recent history of trauma, surgery, or local infections should always raise the index of suspicion for a necrotizing infection. Patient risk factors such as diabetes mellitus, renal insufficiency, malnutrition, immunosupression, or history of intravenous drug use should also raise concern. However, the absence of these conditions should never rule out the possibility of a necrotizing soft tissue infection.