Teaching Case

We report the case of an 85 year old non-insulin-dependent diabetic woman, complaining a clinical history of obstructive chronic bronchopneumopathy (COBP) and high blood pressure.
She underwent our attention because of a severe abdominal pain involving also the right inguinal region, lasting for three days.

Patient was tachycardiac and febrile (38°C). Haematochemical exams revealed a mildly increased percentage of neutrophils. Physical examination did not show any pathological sign, in discordance with the strong pain. The patient underwent X-rays of the hips that resulted to be normal. Anyway, the patient remained under observation because of the increasing pain; at physical examination, performed after 3 hours, a warm swelling of the right inguinal region was detected. At palpation, crepitus was also appreciable. The overlying skin was mottled (Fig 1). Haematological examinations showed a further and higher increase of neutrophils percentage. X-rays were repeated, revealing the presence of abdominal air-fluid levels and confirming the suspicion of subcutaneous emphysema (Fig 2). A CT examination was performed (Fig 3) and it revealed a marked involvement of the upper right thigh and hip by gas. The air tracked both to the back, dissecting along the gluteus fascial plane, and forward, involving the subcutaneous up to the symphisis. Gas was also tracking through the inguinal canal up to the pelvis and along the iliac muscle and the iliac vessels up to the carrefour. Moreover, the increased attenuation of the subcutaneous fat suggested oedema. On the basis of CT findings, diagnosis of necrotizing fasciitis (NF) was posed. The patient underwent a laparoscopic exploration that showed the leak of gas and purulent fluid, and an oedematous but not necrotic muscle. Lateral and medial fasciotomies were performed. Microbiologic analysis on the drained fluid showed a polymicrobial involvement. The patient died 3 hours after the diagnosis.

Necrotizing fasciitis (NF) is a rapidly progressive and often fatal infection representing a surgical emergency. It is characterized by the extensive necrosis of the deep fascia associated to the necrosis of the subcutaneous tissues, usually accompanied by severe systemic toxicity. NF is relatively rare, although its prevalence is arising because of the increasing number of immunocompromised patients (due to HIV infection, diabetes, cancer, alcoholism, intravenous drugs abuse, peripheral vascular disease, or organ transplants). Predisposing factors include underlying infections, minor trauma, surgery or even insect bites, although it can also be idiophatic, as in scrotal or penile necrotizing fasciitis (Fournier Gangrene) [1,2,3]. The most common type (type I) of NF is a polymicrobial infection with both aerobic and anaerobic organisms such as Clostridium, Proteus, Escherichia Coli, Bacteroides, and Enterobacteriaceae. A second form (type II), monomicrobial, is mostly caused by group A Streptococci and represents approximately 10% of cases. Clinical presentation is often nonspecific in the early stages, being characterized by fever and malaise, mild erythema, and un-proportional local pain due to fascia necrosis. Laboratory examinations usually show only a mild increase of neutrophils. In the advanced stages, a progression to brawny oedema and tenderness may be appreciated and crepitus can be recognized in about 50% of patients [1,4,5]. The overlying skin is classically warm and indurated, with mottled, purple patches. Toxic shock syndrome may complicate 10% of cases. The rapidity of spread requires rapid diagnosis, which may be facilitated by imaging. The most common plain radiographic finding is gas in the soft tissues, although this is seen in only few cases. Frequently, plain radiographs are normal until infection and necrosis are advanced. Ultrasound examination may demonstrate thickened fascial planes and fluid accumulation. The presence of gas, potentially limiting the exam, may represent a diagnostic finding [1,4]. Anyway CT, as well as MR, plays a major role in suggesting the diagnosis. Differential diagnosis must be posed between NF and other affections as cellulitis or nonnecrotizing fasciitis. A specific sign of NF at CT examination is the involvement of deeper structures than those of cellulitis, the presence of gas in subcutaneous, the thickening of the involved fascia, fluid collections along the fascial sheaths, and the extension of oedema into the intramuscolar septa. At contrast-enhanced CT, there is no demonstrable enhancement of the fascia, a finding that confirms the presence of necrosis and helps in distinguishing nonnecrotizing fasciitis from NF. At MR study, NF is depicted by areas of low signal intensity within the subcutaneous soft-tissues and by increased intensity signal on T2-WI Particularly, MR can better demonstrate, in the early stages, the presence of purulent perifascial fluid and oedema, showing increased signal intensity on both sides of the fascia on fluid-sensitive images [3]. One of the most important predictors of mortality in NF is delay in diagnosis. Surgical debridement, early fasciotomy and aggressive antibiotic therapy are the therapeutic strategies for these patients. The mortality rate may be as high as 30-70% because of sepsis, respiratory failure, or multi-organ system failure [1,2,5].