Well-differentiated Neuroendocrine Tumors

Comments:
Macroscopic Features: As in other locations, well-differentiated neuroendocrine tumors (WDNETs) of gallbladder and bile ducts form homogenous, yellow or grey-white, firm submucosal nodules. Some are polypoid and resemble intracholecystic papillary neoplasms. They may also have an associated intraepithelial papillary neoplasm.

Microscopic Features: They show a uniform population of tumor cells with an insular, trabecular, or tubular growth pattern. The cells have moderate amount of eosinophilic cytoplasm and round, uniform nuclei with finely stippled chromatin (salt and pepper appearance). Tumors associated with von Hippel-Lindau syndrome may show clear cytoplasm. Mitoses are present but there is no necrosis.