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A 39-year-old woman complains of continually increasing pain in her right knee with swelling of the popliteal fossa. Injuries and pre-existing conditions are denied. On clinical examination, an indurated, non-compressible mass is found in the popliteal region. Flexion is limited. X-rays and MRI of the knee are performed.
On x-rays, there is a inhomogeneous soft tissue swelling in the popliteal fossa, as well as a cystic, polygonal lesion with marginal sclerosis in the distal, dorsal segment of the femur. MRI demonstrates a large, oval mass extending in the soft tissues of the popliteal fossa and growing deeply into the femur from the dorsal side. In the T2* gradient-echo sequence, the signal intensity of the lobulated mass appears strongly hypointense. The popliteal artery is displaced medially and supplies pathological vessels to the tumor.
What is your diagnosis?
