My cyst was smaller than that and before surgery they said it was 60% chance benign and 40% cancerous. It did turn out to be benign but there was cancer not far from it. I am lucky they did surgery as probably would have been much worse now as I had surgery Dec 13 and elected to do survelience only and no chemo. Mine was on the head so not sure about the neck situation. Surgery called the whipple which you can check out on line.