Introduction
Neuroendocrine neoplasms (NEN) often occur in the pancreas (P-NEN) and
gastrointestinal tract (GINEN) [1]. Gallbladder (GB) NEN is rare and
accounts for only 0.5% of all NEN and 2% of all gallbladder tumors
[2]. Furthermore, patients with GB-NEC have poor prognosis [3].
Currently, there are no diagnostic imaging findings for GB-NEC. For NEC,
a platinum-based regimen is commonly used, but there is only one report
suggesting effectiveness of nivolumab [4]. Here, we report a case
involving successful treatment of GB-NEC with nivolumab.