Synovial Sarcoma

During the lateral sagittal plane examination, the tissue surrounding the tendon of the long digital extensor muscle appears to be the same tissue that projects distally toward its bursa.

During transverse examination of the area of the femoral trochlea, the same tissue is seen occupying the joint space and protruding proximally toward the supratrochlear bursa.

In the sagittal plane above the supratrochlear bursa, the abnormal tissue is seen filling the bursa completely.

Doppler evaluation of tissue showed mild perfusion.
These findings led to the suspicion of an intra-articular neoproliferative process. Orthogonal knee X-rays and a chest X-ray analysis were performed, as well as a fine-needle aspiration of the abnormal tissue.

No pathological findings were found during the four-view chest X-ray analysis.

The orthogonal projection of the knee showed osteolysis foci in a moth-eaten pattern in the proximal tibial epiphysis with moderate  cortical involvement and no evident periosteal reaction. The infrapatellar adipose body showed an area of tissue density that projected towards the supratrochlear bursa, causing the patella to separate from the femoral trochlea. An aggressive tibial lesion associated with intra-articular tissue/fluid was noted.

A fine-needle tissue aspiration was performed in the area of the supratrochlear bursa.

The specimen is moderately cellular with slight hemodilution. Large individualized cells are present with marked anisocytosis and anisokaryosis, and a variable N:C ratio. The cells have an oval to fusiform shape with basophilic cytoplasm and an oval nucleus with finely punctate chromatin, and prominent nucleoli are often seen.