No they need to do an MRI. This will tell u if it is benign. Btw you can have it removed u know it is a complicated procedure and involves risk what u need to do is go to a liver specialist. Not sure where you live but find one. Dr Schiano in nyc is one of the best.
I don't think they can tell if a tumor is benign or not by 'looking' at it. It usually does require a biopsy. Have they seen any fluid in the abdomen in all your scans? Also, usually a hemangioma is benign, but I don't think they can be confused with actual tumors. Either way, just go the Emergency Room. If your pain is bad, something is going on and they shouldn't let you leave until they find out why. Good luck!