Hepatoid carcinoma of the pancreas in a patient with familial adenomatous polyposis

A man in his fourth decade of life was found to have an incidental, minimally symptomatic 18-mm distal pancreatic mass on imaging during workup of newly diagnosed familial adenomatous polyposis (FAP). EUS with fine needle aspiration demonstrated hepatocytic differentiation concerning for metastatic hepatocellular carcinoma, yet no liver lesions nor distant metastatic disease were noted on imaging. Tumour markers were not elevated, and next-generation sequencing demonstrated no somatic mutations. A multidisciplinary tumour board determined that diagnosis and treatment of the pancreatic lesion was indicated prior to colectomy for FAP. He underwent a robot-assisted distal pancreatectomy with splenectomy and pedicled falciform ligament flap. Pathology yielded a stage 1 (pT1cN0) moderately differentiated hepatoid carcinoma. He then underwent a prophylactic total proctocolectomy with ileoanal pouch anastomosis for FAP. He was later found to have an enlarging mesenteric desmoid tumour at the level of L5 and is presently treated with gamma-secretase inhibitor therapy.