Erosion of Distal Femur, Loss of Collateral Ligament

Patient had history of severe left knee pain.

Figure 1A. AP and lateral radiographs of the knee show soft tissue swelling, bone erosions with overhanging edges, and soft tissue masses with tiny calcifications.

Figure 1B. AP and lateral radiographs of the knee show soft tissue swelling, bone erosions with overhanging edges, and soft tissue masses with tiny calcifications.

Figure 2A. Axial T2 GRE shows low signal intensity of the tophi.

Figure 2B. Axial PD FS intermediate signal intensity of the tophi.

Figure 2C. Axial T1 FS intermediate signal intensity of the tophi.

Figure 3A. Coronal STIR heterogeneous but predominantly low signal intensity of the tophi.

Figure 3B. Coronal T1 low signal intensity of the tophi.

Figure 4A. Sagittal T2 FS heterogeneous but predominantly low signal intensity of the tophi.

Figure 4B. Sagittal T1 low signal intensity of the tophi.

Figure 4C. Sagittal PD intermediate signal intensity of the tophi.

Figure 5A. Axial T1 FS post IV contrast.

Figure 5B. Sagittal T1 FS post IV contrast.

Figure 5C. Coronal T1 FS post IV contrast shows heterogeneous avid enhancement of tophi.

Diagnosis: Tophaceous Gout

MRI of gout may demonstrate generic features of inflammation including synovial thickening, effusions, bone erosions, and bone marrow edema.

The phases of gout include asymptomatic hyperuricemia, acute gout, asymptomatic phase between gouty attacks, and chronic tophaceous gout.

Tophi may show intense contrast enhancement due to hypervascular soft tissue and granulation tissue.

Gout is inflammatory arthritis due to the accumulation of monosodium urate crystals in joints and soft tissues.