Large Cell Neuroendocrine Carcinoma of the Rectum Presenting with Extensive Metastatic Disease
Figure 2
((a) and (b)) Large cell neuroendocrine carcinoma infiltrating the connective tissue stroma of the colorectal biopsy, as nests of cells. There is associated tumor necrosis (arrows). Normal colonic mucosa is visible at the top of the field in (a). (c) The neoplastic cells reveal hyperchromatic nuclei with inconspicuous nucleoli, and a mitotic figure (arrow) is visible to the left, in the nest of neoplastic cells. ((d), (e), and (f)) On immunohistochemical staining the neoplastic cells stained positive for synaptophysin (diffuse cytoplasmic brown staining), chromogranin (focal cytoplasmic brown staining), and expressing a high Ki-67 labeling index of up to 50% cells (brown nuclear staining).
