Tophaceous gout of the knee: Revisiting MRI patterns in 30 patients

OBJECTIVE:: To evaluate the locations and associated erosions of tophaceous gout in the knee and to reevaluate its characteristic magnetic resonance imaging features. MATERIALS AND METHODS:: We performed a retrospective review of the magnetic resonance (MR) images of the knees of 30 patients with histopathologically confirmed gouty tophi. Each tophaceous lesion was evaluated for location, morphology, signal intensity, and associated bone erosion or intraosseous involvement. RESULTS:: The tophaceous masses were commonly located on the medial aspect of the infrapatellar fat pad and anterior joint recess (n = 28, 87%), the space adjacent to the lateral rim of the lateral femoral condyle (n = 25, 78%), and the intercondylar fossae (n = 22, 69%). All tophaceous lesions showed similar signal characteristics (low-intermediate signal intensities on T1-weighted images, with heterogeneous signal intensities on T2-weighted images), and 3 morphologic patterns were observed: amorphous masses (n = 27), linear crystalline-like deposits (n = 6), and cystic lesions of the bursae around the knee (n = 3). Associated bone erosions occurred in the lateral rim of the lateral femoral condyle (n = 8), the roof of the intercondylar notch (n = 7), the tibial eminence (n = 5), and the medial and lateral rim of the tibial plateau (n = 3). Intraosseous tophi were seen in the tibial plateau (n = 3) and patella (n = 1). CONCLUSION:: Knowledge of the common locations and associated erosions of tophaceous gout and its characteristic MR appearance may facilitate its correct diagnosis with magnetic resonance imaging, particularly in patients with no clinical symptom or only an isolated lesion on MR images.