Fig. 2

Photomicrographs of biopsy specimens from the ampulla of Vater. a, b Hematoxylin and eosin stain a showing atypical columnar epithelial cells suggestive of adenocarcinoma. Hematoxylin and eosin stain b of another specimen showing solid proliferation of epitheloid cells. The tumor cells are positive for chromogranin A and synaptophysin. Scale bars (black lines, bottom right): 100 µm (a) and 50 µm (b)