Are there other options for someone too large for surgery with a cyst between 4th & 5th vertebrae?

Change what you can: Your surgeon is giving you good, sound advice. Being too large is difficult, but controllable by you. For your surgeon to proceed with your cyst, before, weight loss would add unnecessary risk to your long term health. It is hard to hear, the increased surgical risk with a "too large" patient changes the risk/benefit curve to non-operative therapies. Lose the weight, then get your cyst resected.

Cysts: The answer is really what kind of cyst and what are the symptoms. Usually benign cysts are not bothersome unless they are pressing on structures like the nerve. Many interventional pan doctors or radiologists may be able to place a needle into the cyst - depending on where it is.