Clinicopathological Criteria Defining Mucinous Appendiceal Tumors from 2476 Appendectomies: a Single-Center Retrospective Study

J Gastrointest Cancer. 2020 Mar;51(1):10-16. doi: 10.1007/s12029-018-0182-4.

Abstract

Objectives: Mucinous appendiceal tumors (MATs) constitute 0.2-0.3% of appendectomies. This retrospective chart review study determines the incidence of MATs among appendectomies at King Abdul-Aziz Specialist Hospital, Taif City, Saudi Arabia, from January 2009 to December 2014. The clinicopathological features, histopathological criteria, management, outcomes of patients, and the impact of histopathological classification on the follow-up period and recurrence are evaluated.

Methods: Demographic and clinicopathological data were collected from medical records. Microscopic slides from 2476 appendectomies were re-examined to diagnose and classify MATs into low-grade mucinous neoplasms (LAMNs) and mucinous adenocarcinomas (MACAs). CK20, CK7, and cdx2 immunohistochemistry was applied for evaluating pseudomyxoma peritonei. Data were expressed as numbers, percentages, and mean ± standard deviation.

Results: Nine MATs were diagnosed with an incidence of 0.36% of appendectomies, a male:female ratio of 1.25:1 and a mean age of 57.2 years. Acute appendicitis was the commonest clinical presentation. About 66.7% were LAMNs and 33.3% MACAs. Beside appendectomy, MACAs were managed with right hemicolectomy and chemotherapy. The median follow-up was 34 months with recurrence and liver metastases in two MACAs. No recurrences for LAMNs.

Conclusions: MATs constitute 0.36% of all appendectomies. Classifying MATs into LAMNs and MACAs is more applicable for both clinical and pathology practices as compared to the three- or four-tiered classification schemes.

Keywords: Acute appendicitis; Histopathological classification; LMANs; MACAs; Mucinous appendiceal tumors; Pseudomyxoma peritonei.