Nodular fasciitis: characteristic imaging features on sonography and magnetic resonance imaging

The purpose of this study was to evaluate the imaging features of nodular fasciitis on sonography and magnetic resonance imaging (MRI).

A retrospective search of the radiologic and pathologic databases over the past 10 years for the diagnosis of nodular fasciitis was performed. Sonographic and MRI features were described. Pathologic specimens were reviewed.

Six pathologically confirmed cases of nodular fasciitis were found. The mean patient age was 19.5 years (range, 8-33 years); 3 patients were male and 3 were female. Four patients had sonography only; 1 patient had both sonography and MRI; and 1 patient had MRI only. Three masses were located in the subcutaneous tissue adjacent to fascia; 2 were at the subcutaneous/muscular border; and 1 was intramuscular; however, all were in contact with fascia and showed a fascial tail on sonography and MRI. On sonography and MRI, masses were oval with poorly defined lobulated borders, averaging 2.6 cm (range, 1.8-3.5 cm). On sonography, all masses were hypoechoic. On MRI, the masses were isointense to muscle on T1-weighted sequences, hyperintense to muscle on fluid-sensitive sequences, and enhanced avidly but heterogeneously. The masses were surrounded by fat.

When a rapidly growing oval mass in contiguity with a fascial plane is recognized, the diagnosis of nodular fasciitis should be entertained. More importantly, the possibility of an inaccurate diagnosis by core biopsy exists, which may warrant gross resection.