Age / Sex : 37 / M

Age / Sex : 37/M

Chief complaint : Left thigh painful swelling for 3 days, on Cyclosporine medication following kidney transplantation

necrotizing fasciitis

Discussion

Findings:

a. Axial fat-suppressed T2-weighted image shows peripheral band-like high signal intensity (arrows) in the involved muscles of the anterior, medial, and posterior compartments of left thigh. Hyperintense signal is seen along the deep fascia (arrowheads) as well as superficial fascia.

b, c. Axial T1-weighted image (b) and fat-suppressed contrast-enhanced T1-weighted image (c) show peripheral band-like enhancement (arrows) of involved muscles and thin smooth enhancement of deep fascia (arrowheads). The patient had emergency fasciectomy. Streptococcus pyogenes was cultured.

d. Histopathologic specimen reveals marked neutrophilic and histiocytic infiltrates and necrosis(*) of fascia (H-E, X200)

e. Photomicrograph of histologic specimen shows severe inflammatory changes and necrosis (*) in the muscle (H-E stain, X100).

Differential Diagnosis:

Cellulitis, Pyomyositis, Eosinophilic fasciitis, Lymphedema, Phlebedema

Diagnosis: 

Necrotizing fasciitis

Discussion:

Necrotizing fasciitis is a rapidly progressive, life-threatening illness characterized by necrosis and suppuration. It is often difficult to differentiate necrotizing fasciitis from cellulitis or pyomyositis with the initial clinical presentation. However, prompt and aggressive surgical treatment is required to prevent a fatal outcome in patients with necrotizing fasciitis, whereas, other soft tissue infections such as pyomyositis or cellulitis do not require emergency surgery. Necrotizing fasciitis can only be confirmed during surgery: extensive undermining of the surrounding tissue is typically observed and the facial plane lacks resistance to a blunt instrument. Common MR findings of necrotizing fasciitis include peripheral band-like hyperintense signal in muscles on fat-suppressed T2-weighted images, peripheral band-like contrast enhancement of muscles, thin smooth enhancement of superficial and deep fascia, subcutaneous involvement, and multicompartmental involvement.

References:

1.     Schmid MR, Kossmann T, Duewell S. Differentiation of necrotizing fasciitis and celluitis using MR imaging. AJR 1998;170:615-620 

2.     Seok JH, Jee WH, Chun KA, et al. Necrotizing fasciitis versus pyomyositis: discrimination with using MR imaging. Korean J Radiol 2009;10:121-128