Presentation
Investigation for hematuria.
Patient Data
There is a solid mass involving the tip of the appendix associated with surrounding stranding and likely venous invasion. Small calcifications are noted around the lesion. Uncomplicated colonic diverticular disease noted. The bowel is otherwise unremarkable.
Apart from a right cortical and left para pelvic simple renal cysts (Bosniak I), both kidneys are unremarkable. Renal collecting system, ureters, and bladder do not show suspicious lesions or obstruction.
Histopathology
Macroscopy: Labeled "Right hemicolectomy.' Specimen comprises terminal ileum 500 mm in length by 50 mm in circumference with up to 40 mm of attached mesenteric fat, cecum 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 cecum 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 cecal 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 fecolith. 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 tumor 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. Tumor 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. Tumor is confined to the distal and midportion of the appendix, with no invasion of the adjacent cecum. 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 tumor 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 cecum.
- No lymphovascular invasion identified.
- Resection margins clear.
- No metastatic tumor in 22 lymph nodes (0/22).
- pT3 N0 MX.
Case Discussion
The CT findings are those of a solid appendiceal tumor, with differential diagnosis including an adenocarcinoma or neuroendocrine tumor. Lymphoma and mucinous neoplasms were considered less likely given the focal solid enhancing pattern of the lesion.
This patient underwent right hemicolectomy with further confirmation of a pT3 N0 Mx Goblet cell carcinoid of the appendix, likely in the category signet ring cell type (Group B) of Goblet cell carcinoid.
The WHO classification of tumors states that Gobled cell carcinoid tumor exhibits both neuroendocrine and glandular differentiation, but is a distinct epithelial tumor from classic neuroendocrine carcinoma or adenocarcinoma. As you can imagine, this can pose a challenge to pathologists in classifying the tumor.
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