Very complex case. Classical finding of main duct mucinous neoplasm of the pancreas, which carries around a 65% risk of harboring carcinoma.

The key to understanding the mesenteric findings is noticing that this patient had a total colectomy, and then asking "why?". 

At the time of this dictation, no additional history was given, therefore, this fact was (cruelly) withheld from the presentation. This patient underwent total colectomy many years prior for familial polyposis and resection of desmoid tumor in the 70's. 

This is a great example of a more insidious appearance of intra-abdominal desmoid, which can have a mass-like, infiltrative, or combined appearance. FAP patients are at particularly notable risk after colectomy. 

Companion solid mesenteric desmoid.