Pancreatic adenosquamous carcinoma and intraductal papillary mucinous neoplasm in a CDKN2A germline mutation carrier

A 69-year-old woman from a kindred with familial atypical multiple mole melanoma and carrier of a germline mutation in CDKN2A, presented with abdominal pain caused by a solid-cystic pancreatic mass. The patient had an abdominal computed tomography three years before in which there was no evidence of pancreatic lesion. The endoscopic ultrasound guided fine needle aspiration showed adenocarcinoma with squamous component. After surgical resection the final diagnosis was adenosquamous pancreatic carcinoma (ASPC) arising in an intraductal papillar mucinous neoplasm (IPMN). Adenosquamous carcinomas are uncommon in the pancreas and have rarely been described in association with IPMNs. It has worse prognosis than the ordinary pancreatic ductal adenocarcinoma and some distinct features. We review the clinical, imaging, pathologic and molecular aspects of ASPC. Differential diagnosis with contamination, squamous metaplasia and pancreatic metastases from a distant squamous carcinoma is discussed. Besides, the case is an accelerated model of the adenoma (IPMN)-carcinoma sequence probably due to the CDKN2A germline mutation. Somatic CDKN2A mutations are common events in the early steps of sporadic pancreatic cancer, but germline mutation carriers have a significantly higher risk of pancreatic carcinoma.