Gangliocytic Paraganglioma With Atypical Immunohistochemical Features Presenting as Extrahepatic Biliary Obstruction.

Gangliocytic paraganglioma is a rare benign tumor of upper gastrointestinal tract that most commonly involves the second part of duodenum. The tumor is detected incidentally on imaging in most of the cases. However, presentation with extrahepatic biliary obstruction is extremely rare. We recently encountered a 50-year-old male patient who was evaluated for extrahepatic biliary obstruction and was found to have a periampullary mass on imaging. The patient underwent pylorus-preserving pancreaticoduodenectomy along with liver biopsy and hepatoduodenal lymph node dissection. On histopathological examination, a tumor was detected in the periampullary region of duodenum, which was confirmed to be gangliocytic paraganglioma on immunohistochemistry along with atypical histological and immunohistochemical features.