18 F-FDG PET/CT Findings Mimicking Gallbladder Metastasis From a Rectal Adenocarcinoma: Rare Synchronous Gallbladder and Rectal Cancer.

Metastasis from rectal adenocarcinoma (RAC) to the gallbladder (GB) is rare. Differentiating GB metastasis from primary gallbladder cancer (GBC) is important for treatment planning. A patient diagnosed RAC with 18 F-FDG PET/CT found suspicious findings of GB metastasis. However, after surgery was found to be primary GBC. The incidence of multiple primary tumors (MPTs) varies 2.4%-8%. In this case report, we would like to present 18 F-FDG PET/CT findings of rare synchronous coexistence of GBC and RAC, and also that, although rare, metastasis from the RAC to the GB should definitely be kept in mind.