case_images: PMC10879725_01
case_images: CT scan of abdomen/pelvis demonstrating a mass obstructing the common bile duct.. A: Coronal CT image demonstrating a mass (purple asterisk) in the distal-most aspect of the common bile duct with marked intra- and extra-hepatic biliary duct dilatation. B: Axial CT image demonstrating a mass that is partially obstructing the distal common bile duct (yellow arrow).
case_images: cureus-0016-00000052729-i01.jpg
case_images: PMC10879725_01_cureus-0016-00000052729-i01.jpg
case_images: FIG1
case_images: A CT scan of the abdomen and pelvis revealed a soft-tissue density measuring 1.9 x 1.5 x 1.9 cm within the distal common bile duct with marked intra- and extrahepatic bile duct dilatation, and variable pancreatic duct dilatation (Figure 1).
case_images: Fine needle aspiration cytology of common bile duct mass.. A-B: Diff-Quick stain at 20x and 40x, respectively, showing single cells and scattered sheets of tumor cells with round to ovoid pleomorphic nuclei. Admixed are a few cells consistent with epithelial dysplasia. C: 20x Papanicolaou stain demonstrating sheets of tumor cells. D: Thin preparation nicely highlights the salt and pepper chromatin. E-F: Cell block at 20x and 40x, respectively, showing sheets and groups of cells with round to ovoid pleomorphic nuclei, salt and pepper chromatin, frequent mitotic figures, and inconspicuous nucleoli.
case_images: cureus-0016-00000052729-i02.jpg
case_images: PMC10879725_01_cureus-0016-00000052729-i02.jpg
case_images: FIG2
case_images: The biopsy results from the FNA demonstrated a well-differentiated neuroendocrine tumor: WHO, Grade 3 (Figure 2).
case_images: Surgical histology of common bile duct mass.. A: 40x view of biliary epithelium adjacent to the tumor showing high-grade dysplasia. Note the frequent mitosis toward the luminal surface (blue arrows). B: 20x view of the neuroendocrine tumor with nested architecture. C: 40x view where neuroendocrine features can be appreciated characterized by salt and pepper chromatin. D-E: The tumor expresses synaptophysin and chromogranin immunohistochemical stains, respectively, supporting the neuroendocrine differentiation. F: MIB-1 staining shows a high Ki-67 proliferative index (>80%).
case_images: cureus-0016-00000052729-i03.jpg
case_images: PMC10879725_01_cureus-0016-00000052729-i03.jpg
case_images: FIG3
case_images: Similarly, the forceps biopsy from the bile duct stricture showed sheets of neoplastic cells with oval nuclei, salt-and-pepper chromatin, and a small amount of cytoplasm (Figure 3).