A case of an intussuscepted neuroendocrine carcinoma of the appendix

Figure 1 Endoscopic appearance of polypoidal lesion in the cecum.

Figure 2 Gross specimen of invaginated appendiceal tumor seen on opening cecum.

Figure 3 Well-differentiated neuroendocrine carcinoma, arranged in nests and trabeculae, beneath uninvolved large-intestinal type appendiceal mucosa (top left hand corner) (hematoxylin and eosin; ×16).

Figure 4 Chromogranin positive immunohistochemical staining (brown cytoplasmic staining) demonstrating neuroendocrine differentiation of tumor cells (×40, 1:5 000 dilution, DAK-A3 clone, DAKO, Cambridge, UK).