Presentation
Knee pain with swelling since one year. No history of trauma.
Patient Data
Lytic lesions noted in the proximal tibia and lateral femoral condyle.
There is cortical breach seen at tibial bicondyles.
No features of secondary osteoarthritis or calcification or osteoporosis.
Incidental fabella sesamoid bone also seen.
There are multiple lobulated soft tissue masses seen arising from the anterior/posterior recesses of knee joint and supra/infrapatellar bursa. These masses are of intermediate signal intensity on T1 and hypointense on T2. Intramass signal voids (hemosiderin deposits) and cystic changes noted.
Secondary changes of pressure effect noted in the form of erosions in the proximal tibia and lateral femoral condyle. Edema seen in the bilateral gastronemius and vastus lateralis muscles.
The ligaments and menisci are normal in morphology.
Special thanks: Dr Anand H K
Case Discussion
Radiologically this is a typical case of diffuse pigmented villonodular synovitis with secondary pressure effect on tibia/femur and adjacent muscles.
Editor's note: Per the 2020 WHO Soft Tissue and Bone Tumors Classification (5th ed.), the recommended terminology is tenosynovial giant cell tumor with pigmented villonodular synovitis no longer recommended (although remains in common use).