Tumors of exocrine and endocrine pancreas
The pancreas can have cystic or solid neoplasia, but not all cysts are neoplastic! Only 5-15% are. Let's take a look at some of our cysts!
Serous Cystadenomas account for 25% of cystic neoplasms, they are composed of glycogen rich cuboidal cells within which sits fluid. These are entirely benign, and surgical resection is curative.
Mucinous cystic neoplasms are almost exclusively female and arise in body or tail of pancreas. The cystic spaces are filled with thick, tenacious mucin and the cysts are lined with columnar epithelium. Mucinous cystic neoplasms can be defined as low-grade, moderate or severely dysplastic based on cytological examination of epithelial lining.
Intraductal papillary mucinous neoplasms are mucin producing intraductal neoplasms, occurring more frequently in men. They arise in the pancreatic duct, and show various grades of dysplasia, sometimes with invasive adenocarcinoma components.
And now, onto the solids! There's only one we really care about here, and that’s infiltrating ductal adenocarcinoma of the pancreas, commonly called pancreatic cancer. High death rate, arises due to inherited and environmental conditions. KRAS oncogene is most frequently altered (impairing GTPase of Kras protein) along with p16 inactivation (a tumour suppressor). The majority of these adenocarcinomas arise in the head (60%) and body (15%). They appear as hard, grey-white, poorly defined masses. It is a highly invasive cancer and causes a strong non-neoplastic host reaction (desmoplastic response). They generally obstruct the common bile duct when found in the head, and this gives first symptoms, if in the tail, it is generally very late before they are identified. Differentiation of the cells is generally poor and dense stromal fibrosis can be seen along with lymphatic invasion.
H&E: ductal adenocarcinoma of the pancreatic head – atypical, irregular glands with large pleomorphic nuclei in fibrous (desmoplastic) stroma; tumour cells wrap around a nerve (oval, left of centre) – perineural invasion is typical.
Image: “Pancreas adenocarcinoma (1) Case 01” by user:KGH, CC BY-SA 3.0, via Wikimedia Commons.
Remember: endocrine tumours (pancreatic neuroendocrine tumours, from islet cells) are named after their hormone:
- insulinoma – the commonest functioning one; attacks of hypoglycaemia relieved by glucose
- gastrinoma – Zollinger–Ellison syndrome with multiple, refractory peptic ulcers
- glucagonoma – mild diabetes and a migratory necrolytic skin rash
- VIPoma – watery diarrhoea, hypokalaemia, achlorhydria
- several together suggest MEN 1