Tophaceous Gout of the Patella: A Report of Two Cases
Figure 1
(a) AP and (b) lateral radiographs of right knee demonstrate diffuse faint calcification involving the insertion of the quadriceps tendon at the upper pole of the patella (black arrow). Note the well-defined lytic lesion with marginal sclerosis (arrowheads) in the patella and prepatellar soft tissue swelling. (c) AP and (d) lateral radiographs of the right knee a year later show a comminuted pathological fracture of the mid patella involving the lytic lesion (white arrows) with associated joint effusion (star). The faint calcification within the distal quadriceps is again noted (black arrow). Sagittal (e) T1-WSE and (f) T2-WGE and coronal (g) PDSE and (h) STIR MR images confirm a comminuted pathological fracture of the mid and upper patella (black arrows) involving the patellar lesion (white arrows) that displays nonspecific features. However, there is a prominent inhomogeneous soft tissue mass in the prepatellar region, some of which displays low signal intensity (SI) on all sequences that corresponds to the mineralisation noted on the radiographs (arrowheads). (i) Core biopsy at low power and (j) core biopsy at high power, stained with H&E. There are aggregates of amorphous eosinophilic material surrounded by a palisade of histiocytes and giant cells in keeping with tophaceous gout.
