CASE 126

By: Dr. Nizar Al-Nakshabandi MD, FRCPC

HISTORY: 77-year-old male with uncontrolled diabetes complaining of limb pain following foot amputation.

What are your findings?

What is the differential diagnosis?

What are the causes?

FINDINGS:

Transaxial CT scan of the right thigh that demonstrates asymmetrical thickening of the fascia with associated stranding of the subcutaneous fat. In addition, edema is seen to extend between the intermuscular septa and muscle with evidence of streaks of air in them. A collection is not seen.

DIFFERENTIAL DIAGNOSIS:

·        Necrotizing fasciitis.

·        Fournier gangrene if it was extending into the perineum.

·        Postsurgical emphysema.

DIAGNOSIS:

Necrotizing fasciitis of the right lower limb.

PEARLS AND DISCUSSION:

Necrotizing fasciitis is a rare but fatal infection of the soft tissue if not treated quickly. It is a radiological, dermatological and surgical emergency. It is common in the immunocompromised such as the HIV population as well as diabetics and cancer patients.

The common type is the polymicrobial infection with both aerobic and anaerobic organisms such as clostridium and Escherichia coli.

The second most common type is the single organism type group a streptococci [Flesh eating bacteria] which occurs in 10-15% of the cases and can lead to toxic shock syndrome.

Diagnosis is by clinical examination, once suspected always perform a CT scan with no IV contrast to detect the air and fascial thickening. Imaging should not delay the diagnosis and MRI if performed will demonstrate loss of the muscle texture with edema in the fascial planes seen on T2-weighted images.

Mortality rates are high and can reach 75%. Treatment is with surgical fasciotomy and debriment of the necrotic tissues.

FURTHER READING:

1.      Kim KT, Kim YJ, Won lee J et-al. Can necrotizing infectious fasciitis be differentiated from nonnecrotizing infectious fasciitis with MR imaging? Radiology. 2011;259 (3): 816-24. 

2.      Fugitt JB, Puckett ML, Quigley MM et-al. Necrotizing fasciitis. Radiographics. 24 (5): 1472-6

3.      Wysoki MG, Santora TA, Shah RM et-al. Necrotizing fasciitis: CT characteristics. Radiology. 1997;203 (3): 859-63. Radiology