Incidental Well-Differentiated Neuroendocrine Neoplasm This 3-mm, low-grade well-differentiated neuroendocrine neoplasm (WDNEN) (carcinoid) was incidentally found at the gallbladder neck. Cholecystectomy was performed for cholelithiasis. The overlying gallbladder mucosa appears unremarkable.
Nested Growth Pattern Tumor cells of this gallbladder WDNEN show diffuse cytoplasmic immunoreactivity to antichromogranin antibody, which highlights a nested growth pattern. Same staining results are also observed for synaptophysin.
Histologic Features Tumor cells of WDNEN typically have uniform round nuclei, finely stippled (“salt and pepper”) chromatin, inconspicuous nucleoli, and eosinophilic cytoplasm. No mitotic figures or necrosis are seen in this microphotograph.
Clear Cell Variant This WDNEN shows nested tumor cells, the majority of which have abundant foamy cytoplasm due to lipid accumulation . Tumor cells with eosinophilic cytoplasm are also present .
was incidentally found at the gallbladder neck. Cholecystectomy was performed for cholelithiasis. The overlying gallbladder mucosa 
appears unremarkable.
. Tumor cells with eosinophilic cytoplasm are also present 
.
