Intracystic Papillary Neoplasm of Gallbladder Mimicking Metastatic Malignancy on PET/CT.

Intracystic papillary neoplasm of the gallbladder is a rare preinvasive neoplastic lesion with similar characteristics as intraductal papillary mucinous neoplasm and other papillary neoplasms of pancreaticobiliary system. We report a case of 48-year-old woman with a history of recurrent right flank chondrosarcoma and gallbladder lesion on MRI and PET/CT interpreted as indeterminate for metastatic disease. Subsequent cholecystectomy showed intracystic papillary neoplasm. With gallbladder lesions being rare on PET/CT, this case illustrates the importance of considering both primary and secondary tumors in the differential diagnosis.