Is the lump in the back of your knees, fat or fluid? If it is fat, can it be lipo'ed?

A Baker cyst any fatty deposits are to completely distinct entities. I don't really see how they would be clinically confused. I've never heard of fat accumulating in the back the knees that was accessible to liposuction.

If the lumps you're describing consist of fat, they certainly can be
treated with liposuction. If they are the only fat pockets you have,
the procedure would be quick and pose an easy recovery.
Before
considering liposuction, however, a definitive diagnosis is in order.
You may want to consult another doctor and consider ultrasound. That
could confirm whether the lumps are filled with fluid or fat without too
much expense.
Elliot Jacobs, M.D.New York Plastic Surgeon

There is quite a difference between a Baker's cyst and fat.  Ultrasound will clearly demonstrate the distinction between the two.  Baker's cysts can be aspirated although there is a difference of opinion on whether the benefit would be long lasting.  You are quite fortunate not to have any pain.  Classically, Baker's cysts are associated with pain and/or shooting "warmth" down the legs.  Try ice compresses and massage as modalities to reduce the cysts, if that is what they are.  Good luck!