The key diagnosis should give us idea about the origin and the biology of the disease, as this is closely related with the treatment plan and prognosis. None of the imaging modalities nor clinical presentation can provide safe data about nature of the tumor. However they are only available tools for staging, response evaluation and follow-up. Histology remains the most used method, but recently presented at ASCO GI meeting pilot study from MDACC group probably will change that – the use of 92-gene classifier for profiling periampullary cancer seems promising. Find abstract here:

http://meeting.ascopubs.org/cgi/content/abstract/31/15_suppl/4133?sid=6d9764a6-c898-4f51-a8be-e96c0adb6334

Dear Yosep

The most reliable method for the determination of origin is the gross evaluation. One should try to determine the main tumor mass/ tumor center.

Exulcerated cavitated tumors in duodenum/ ampulla are most probably carcinomas of papilla Vateri or seldom primary duodenal carcinomas.

If the distal bile duct is involved, the point is, whether the bile duct is more longitudinal infiltrated with lesser invasion to the pancreas - in this case we have a distal bile duct carcinoma. Vica versa, if the main mass located in the pancreas with segmental involvement of the bile duct/papilla - we have a primary pancreatic carcinoma.

Histology helps to limited extent only , but if you have an intestinal type adenocarcinoma , it is probably originated from papilla or seldom from duodenum.

Pancreatobiliary carcinomas may come from papilla, distal bile duct or pancreas as well.

Volkan Adsay addressed this question in this paper http://www.ncbi.nlm.nih.gov/pubmed/23026934

and he keeps intensively working on this issue.

Best regards Bence

The most reliable method is pathological evaluation of specimen with immunostaining