Pes anserine bursitis - an extra-articular manifestation of gout.

While hospitalized with polymyositis, a medically complex 56-year-old male experienced an acute exacerbation of gout. Both ultrasound and magnetic resonance imaging cross-sectional modalities were used to detect, localize, and characterize a soft tissue mass. The tumor was ultimately found to be secondary to gouty inflammation of the pes anserine bursa, a previously unrecognized manifestation of acute gout.