The biopsy location is 
the duodenum.

Note the presence of the
surface mucosal villi and 
the Brunner's glands in the
base of the mucosa.

The diagnosis is adenocarcinoma.

Note the disorganized arrangement
of the lining columnar epithelium,
the nuclear hyperchromasia and 
enlargement and the gland within
gland pattern.

It could not be determined from
the biopsy alone, if this neoplasm
is originating in the ampulla of 
Vater, the distal common bile duct,
the duodenum proper, or the pancreas
with secondary direct extension into
the duodenum.

That determination is better made 
by the correlation of the biopsy
findings with the endoscopic 
appearance and radiographic imaging

Reference - Click on the reference for abstract.

Pancreatoduodenal carcinomas: A clinicopathologic study of 304 cases.