Solution: The findings on this case are quite obvious. There is an impressive process involving the gall bladder that has significant gall bladder wall thickening, increased enhancement of the gall bladder wall, pericholecystic infiltrative change, and low attenuation within the adjacent liver that could represent edema, or infiltration. Prior to surgery, this was thought to represent an invasive gall bladder cancer, but pathology revealed chronic cholecystitis instead and no malignancy. This has happened on several occasions now and there are some clues that can help us differentiate these two, although not perfectly. First, although there does seem to be an aggressive, invasive process here, there is no real discrete mass identified. Gall bladder cancer is typically associated with a hypovascular mass and associated infiltration (usually irregular) of the adjacent liver and nodal metastases. However, in some cases, it can be essentially impossible to differentiate the two processes.