This uncommon, severe infection involves the subcutaneous soft tissues, including the superficial and deep fascial layers. It is usually seen in the lower extremities, abdominal wall, and perianal or groin area. It is commonly spread from a trauma site, surgical wound, abscess, or decubitus ulcer. Alcoholism, parenteral drug abuse, and diabetes are predisposing factors. Pain, tenderness, erythema, swelling, warmth, shiny skin, lymphangitis, and lymphadenitis are early findings. Later, there is rapid progression of bullae with clear pink or purple fluid and cutaneous necrosis; the skin becomes anesthetic, and subcutaneous gas may be present. Systemic toxicity may be manifest by fever, dehydration, leukocytosis, and frequently positive blood cultures. Type I is polymicrobial and includes anaerobic species. Type II includes group A streptococci.
Necrotizing Fasciitis. Markedly swollen, dusky, erythematous arm with necrotizing fasciitis in an IV drug user. (Photo contributor: Alexis Lawrence, MD.)
Necrotizing Fasciitis. Radiograph of the forearm in Fig. 12.10 showing extensive subcutaneous gas. (Photo contributor: Alexis Lawrence, MD.)
Necrotizing Fasciitis. Large cutaneous bullae on the leg of this patient with necrotizing fasciitis. Note the dark purple fluid in the bullae. (Photo contributor: Lawrence B. Stack, MD.)
Necrotizing Fasciitis. Necrotizing fasciitis with cutaneous necrosis in the inner thigh. (Photo contributor: Lawrence B. Stack, MD.)
Management and Disposition
Prompt diagnosis is critical; if made within 4 days from symptom onset, the mortality rate is reduced from approximately 50% to approximately 10%. Initial treatment involves resuscitation with volume expansion, operative debridement, and prompt initiation of broad-spectrum antibiotics.
Plain radiographs or computed tomography (CT) imaging may detect nonpalpable subcutaneous gas.
Hemolysis and disseminated intravascular coagulation may be present.
Necrotizing Fasciitis. Involvement of the abdominal wall and genitals. (Photo contributor: Kevin J. Knoop, MD, MS.)
Necrotizing Fasciitis. Lower extremity CT demonstrating extensive soft tissue gas. (Photo contributor: Lawrence B. Stack, MD.)