Synchronous detection of SDHA-related gallbladder paraganglioma and pancreatic neuroendocrine tumor.

Primary gallbladder paragangliomas (PGLs) are exceedingly rare. PGLs are extraadrenal neuroendocrine tumors that are morphologically inseparable from intraadrenal pheochromocytomas. PGLs and pheochromocytomas are some of the most heritable tumor types in the body and are often associated with other tumors or part of a genetic syndrome. We report a case of gallbladder PGL presenting synchronously with pancreatic neuroendocrine tumor (NET) and pulmonary IgG4-related disease in a 74-year old male patient with disseminated prostate adenocarcinoma. Due to the high rate of germline mutations and the possible syndromal manifestation of PGLs as well as pancreatic NETs, this patient was offered genetic testing, and a pathogenic SDHA germline mutation was found. Immunohistochemically, there was loss of SDHA and SDHB in the PGL but neither in the NET nor in the prostate adenocarcinoma. To our knowledge, this case is the first report of gallbladder PGL associated with pancreatic NET. It is likely that the identified SDHA germline mutation played a role in the development of gallbladder PGL in this patient.