Doctors told me if was possible, but very rare for tumors in the pancreas to be benign. I'm assuming the results of non malignant are the same thing as benign. I had jaundice also which enabled an early diagnosis. Had the surgery (Whipple) and first results of biopsy from surgery was benign. The surgeon told me she still felt final results of the biopsy would show PC. This is the one that takes two weeks for final results. She was right. I had early stage PC, no involvement with lymph nodes or mets.
I think doctors must assume any tumors on Pancreas are PC, and they treat it aggressively. Even if your situation ends up being non malignant (which would be great news), the tumor still needs to come out as it is causing other problems.
Best wishes for your surgery and a good outcome.