Mucinous neoplasm of the appendix

Case contributed by Dr Jan Frank Gerstenmaier


Monitor progress of appendix (?mucocele)

Patient Data

Age: 78
Gender: Female

Follow up CT


The previously noted appendiceal dilation persists, with posterior high attenuation/calcification. The maximum diameter appears slightly increased now (19 mm). Elsewhere, findings are stable with persisting parapelvic/renal cysts, hepatic cyst and colonic diverticulosis.

CONCLUSION: Slight increase in degree of appendiceal dilation. Features remain consistent with mucocele.



CLINICAL NOTES: no/ evidence of metastatic disease ?mucocele of appendix healthy appendiceal base good margin macroscopically

MACROSCOPIC DESCRIPTION: An appendix 75mm long ranging in diameter between 3mm at the neck and up to 23mm in the mid portion. A small amount of mesoappendix is attached, up to 20mm wide, 7mm thick. The serosa is pale tan and smooth with no wall defect. The middle segment of the appendix appears dilated over a length of 25mm. The resection margin is inked green. On sectioning the entire lumen is filled with and distended by white mucinous material. The mucosa is diffusely flattened and appears focally thickened and tan.

BLOCK DESIGNATION: A - LS from the resection margin. B - LS from the tip of the appendix and area of thickened tan mucosa. C&D - TS from the distended segment with intraluminal material. P4. (GS)

MICROSCOPIC DESCRIPTION: Sections of appendix show a low grade appendiceal mucinous neoplasm composed of a focally undulating and focally eroded single layer of mucin producing columnar cells devoid of atypia. At the base of the ulcer there is extensive dystrophic calcification and a patchy lymphocytic infiltrate. The entire appendiceal mucosa is replaced and the epithelium of this neoplasm abuts the underlying muscularis propria. Large copious amounts of mucin is found within the lumen. There is no evidence of invasion into the underlying stroma. The excision appears complete.

DIAGNOSIS: Appendix: Low grade appendiceal mucinous neoplasm completely excised. No high grade area or evidence of invasive malignancy. Further sections show no further pathology.

Case Discussion

Mucocele is not synonymous with mucinous neoplasm. Mucocele is a descriptive term where the appendix lumen is filled with mucinous material. A mucocele can be due to tumor or mucin accumulation proximal to a stricture which may be inflammatory.

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