PMC9834544_01
(A) Computed tomography scan revealed an irregularly shaped mass at the right colon with circumferential thickening of the colonic wall (Blue asterisk). (B) Gross findings of the right hemicolectomy specimen showing a large mass in the ascending colon measuring 13 x 8 cm and invading the ileocecal valve (Blue asterisk). (C) On cut section, the tumor was nodular, white and yellowish in color. It invaded the colonic wall and extended to the subserosa.
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An abdominal computed tomography scan revealed an irregularly shaped mass at the right colon with circumferential thickening of the colonic wall (Figure 1A). It measured 13.5 x 8 cm and was firm, pale-tan, nodular, circumferential with ill-defined borders, (Figure 1B,C).
(A) Microscopic examination of the colonic mass showing a tumor proliferation arising from the mucosa of the colon and infiltrating the submucosa. It is arranged in lobules of neuroendocrine cells admixed with a population of signet ring-like cells that resemble intestinal goblet cells (Hematoxylin and eosin, magnification x40). (B) Lobules of neuroendocrine cells arranged in organoid patterns admixed with a population of signet ring-like cells that resemble intestinal goblet cells. Extracellular mucin was present and abundant. (Hematoxylin and eosin, magnification x200). (C) Admixed populations of mature goblet cell-looking and mucin-laden cells and granulated monotonous neuroendocrine cells that are arranged in distinctive infiltrative and organoid patterns. Extracellular mucin was present and abundant. (Hematoxylin and eosin, magnification x 400). (D) Alcian blue special stain highlighting extracellular mucin and goblet cells which exhibit voluminous bubbly cytoplasm containing basophilic mucin. (Alcian Blue, magnification x400). (E) Histological examination of the appendix was unremarkable. (Hematoxylin and eosin, magnification x100).
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Microscopically, the colonic tumor demonstrated proliferating neoplastic cells exhibiting both mucinous and neuroendocrine differentiation (Figure 2A-C). The tumor arose from the mucosa of the colon and invaded the subserosa (Figure 2A). The tumor proliferation consisted of nests, cords, tubules, and lobules of neuroendocrine cells arranged in organoid patterns (Figure 2A,B) admixed with a population of signet ring-like cells that resemble intestinal goblet cells arranged in small rounded nests or cords. The neuroendocrine cells had indistinct cell borders, eosinophilic granular cytoplasm, and basally located, moderately atypical nuclei with fine granular chromatin (Figure 2C). The goblet cells had irregular hyperchromatic nuclei and bubbly cytoplasm that contained basophilic mucin (Figure 2C). Alcian blue special stain highlights extracellular mucin and goblet cells (Figure 2D). Histologic examination of the appendix (Figure 2E) was unremarkable and did not disclose any tumor proliferation.
(A) Immunohistochemistry demonstrating strong and diffuse staining of the tumor cells with synaptophysin (Immunohistochemistry, magnification x400). (B) Ki67 staining showed a highly proliferative pattern of 80% (Immunohistochemistry, magnification x400). (C) Immunohistochemistry demonstrating strong staining of goblet cells with MUC2 (Immunohistochemistry, magnification x400). (D) Immunohistochemistry demonstrating strong and diffuse staining of the tumor cells with cytokeratin 20 (Immunohistochemistry, magnification x400).
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Immunohistochemically, the neuroendocrine cell component positively reacted with synaptophysin and chromogranin A (Figure 3A). Ki67 staining showed a highly proliferative pattern of 80% (Figure 3B). The goblet cell component was immunoreactive for MUC2 (Figure 3C), CEA, CDX2, and CK20 (Figure 3D).