Clinics in diagnostic imaging (200). Intra-articular chronic tophaceous gout of the knee

Abstract

A 39-year-old man presented with acute left knee pain and swelling. There was limitation of movement of the knee joint. His past medical history was significant for gout. Computed radiography showed bony erosions that were not typical of chronic tophaceous gout. Magnetic resonance (MR) imaging showed focal deposits within the knee joint, which demonstrated isointense signal to muscle on T1-weighted sequence and intermediate signal on proton density (PD) and PD fat-saturated sequences. There was extensive, similar signal abnormality in the cruciate ligaments, popliteus tendon and lateral meniscus. These findings were in keeping with an intra-articular manifestation of chronic tophaceous gout. The clinical presentation and imaging features are herein discussed, with an emphasis on MR imaging.

Keywords: chronic tophaceous gout; intra-articular; knee; magnetic resonance imaging.

Fig. 1

(a) Frontal radiograph of the left knee. (b) Coronal T1-W; (c) sagittal proton density-weighted; and (d) coronal proton density-weighted fat-saturated turbo spin echo MR images of the left knee.

Fig. 2

(a) CT of the right knee in the axial plane shows a faint radiodense focus at the anterolateral corner, likely within the anterior horn of the lateral meniscus (arrow). (b & c) Colour-coded, post-processed images done with dual-energy CT software using a specialised gout algorithm show monosodium urate crystal (green), cortical bone (blue) and trabecular bone (purple). Note the presence of a urate crystal deposit at the anterolateral joint space corresponding to the radiodense focus seen on CT.

Fig. 3

A 37-year-old patient with end-stage renal failure presented with knee pain. (a) Coronal T1-W turbo spin echo MR image shows increased T1-W isointense soft tissue in the lateral joint space causing erosive deformity of the lateral tibial plateau, in keeping with intra-articular manifestation of chronic tophaceous gout (arrow). (b) Radiograph of the right knee shows a lucent lesion with a narrow zone of transition in the lateral tibial plateau (arrow). Diagnostic considerations include brown tumour or subchondral geode.

Fig. 4

(a) Axial T1-W fat-saturated post-contrast and (b) coronal short tau inversion recovery (STIR) sequences show an enhancing STIR hyperintense, slightly lobulated soft-tissue lesion lateral to the distal femur (arrows). No bony erosion was evident. The lesion was subsequently resected, and the histopathological findings revealed synovial sarcoma.

Fig. 5

(a) Lateral radiograph of the left knee shows multiple intra-articular ossified loose bodies (arrows). (b) Axial gradient-recalled echo sequence shows multiple foci of susceptibility, in keeping with synovial osteochondromatosis (arrow).