US - There is a solid lesion in the suprapatellar region deep to the quadriceps tendon. The lesion is anterior to the distal end of the femur. Patella is noted at the lower pole of the lesion separately.  No effusion is seen in the joint. Quadriceps and patellar tendons and Hoffa's fat pad normal.

MR - Non contrast study -  Similar findings regarding morphology.  Images are NOT available to upload.

Arthroscopy - Lesion was excised. No other abnormality apart from this lesion during the scope.

After all of the above workup, the final proven diagnosis is synovial sarcoma of the knee.

Histopathology -Synovial sarcoma