Histopathology

Macroscopy: Labelled "Right hemicolectomy.' Specimen comprises terminal ileum 500 mm in length by 50 mm in circumference with up to 40 mm of attached mesenteric fat, caecum and ascending colon, 120 mm in length by up to 80 mm in circumference, with a 50 mm of attached pericolic fat and up to 70 mm of mesenteric fat. The appendix is present in the caecum and is 120 mm in length, is up to 19 mm in diameter distally and 10 mm diameter proximally with up to 40 mm of attached mesoappendix. The mesoappendix is adhered to adjacent caecal pericolic fat. The appendiceal serosal surface is tan, smooth and focally congested and firm distally. In the distal 27 mm of the appendix the tip is expanded up to 19 mm comprising firm white appendiceal wall tissue. In this area the appendix wall is up to 6 mm thick and the lumen is narrowed. Elsewhere in the proximal two thirds the appendix wall is up to 4 mm thick. There is no evidence of perforation in this area and lies 55 mm from the appendix base, 550 mm from the proximal margin and 120 mm from the distal margin.  The lumen is stenosed. There is no ulceration or inflammation. There is no faecolith. The segment of small bowel and large bowel mucosa is unremarkable. Multiple reactive lymph nodes are identified 3-8 mm.

Microscopy: The sections taken from the distal portion of the appendix show concentric thickening of the appendiceal wall which contains a highly infiltrative population of tumour cells. These cells are present in small nests, trabeculae and as individuals and comprise a population of signet ring cells with large and cytoplasmic mucin vacuoles, as well as atypical epithelioid cells showing nuclear pleomorphism and nucleolar prominence. Tumour extends from the lamina propria through submucosa and muscularis propria and into the subserosal connective tissue. No dysplasia is seen in the glandular epithelium of the appendiceal mucosa. At the tip, there is an expansile pool of inspissated mucin and histiocytes which is present within the subserosal connective tissue, but does not penetrate the visceral peritoneum. Tumour is confined to the distal and midportion of the appendix, with no invasion of the adjacent caecum. The remainder of the colon and the small bowel are unremarkable. There is no malignancy in 22 pericolic lymph nodes, a few of which contain prominent nodules of dystrophic calcification.
The tumour cells show positive immunostaining for broad-spectrum cytokeratin (AE 1/3), chromogranin, synaptophysin and CD56. Ki67 shows a proliferative index of approximately 60%. The features are of a appendiceal adenocarcinoma (goblet cell carcinoid).

Conclusion: Right hemi colectomy specimen:
Moderately differentiated adenocarcinoma of distal appendix (goblet cell carcinoid type), approximately 27 mm in size, invading subserosal connective tissue.
- Confined to appendix, no invasion of caecum.
- No lymphovascular invasion identified.
- Resection margins clear.
- No metastatic tumour in 22 lymph nodes (0/22).
- pT3 N0 MX.

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