Fig. 1
A CT arterial phase with hyperenhanced polyp in the gallbladder with a peripheral calcification. B Histologically, a mass-forming neoplastic growth of the gallbladder mucosa is seen (H&E). C It is composed of neuroendocrine tumor cells arranged in small solid nests, separated by delicate vasculature, mimicking the paraganglioma (“Zellballen”) architecture (H&E). D–J Tumor cells express chromogranin-A (D) and keratin 8/18 (E), while they are negative for GATA3 (F). They show cytoplasmic and nuclear positivity for S100, while no sustentacular cells are seen (F). Tumor cells express somatostatin (G), and, more focally, pancreatic polypeptide (H). The Ki67 index in the “hot spot” area is 8% (J)
