Clinicopathological Characteristics of Low-Grade Appendiceal Mucinous Neoplasm

Dig Surg. 2021;38(3):222-229. doi: 10.1159/000513973. Epub 2021 Mar 10.


Introduction: Recently, "low-grade appendiceal mucinous neoplasms" (LAMNs) have been proposed as one subtype of appendiceal mucinous neoplasms, characterized by a villous or flat proliferation of mucinous epithelium with low-grade cytologic atypia. The aim of this study was to clarify the clinicopathological characteristics of LAMN.

Methods: In this multi-institutional cohort study, we retrospectively analyzed the clinicopathological characteristics in appendiceal neoplasms patients who underwent treatment from 2000 to 2017.

Results: In total, 922 patients were enrolled, with 279 (30.3%) cases of LAMN, and 93 (10.1%) cases of non-LAMN disease. In comparison with patients with non-LAMN disease, those with LAMN had significantly lower levels of CA19-9 (p = 0.045), a lower frequency of T4 tumors (p < 0.0001), a lower frequency of lymph node metastasis (p < 0.0001), and a lower frequency of distant metastasis (p < 0.0001). Survival analysis revealed that patients with LAMN had a significantly better prognosis than did those with non-LAMN disease (p < 0.001). Among the patients with distant metastasis, those with LAMN had a significantly better prognosis than did those with non-LAMN disease (p = 0.0020), but among the patients without distant metastasis, the difference between the 2 groups was not significant (p = 0.26). However, among patients who underwent complete resection, the difference in prognosis between the 2 groups was not significant (p = 0.10).

Conclusions: A multicenter retrospective study revealed that the clinicopathological characteristics of LAMN was different from those of non-LAMN.

Keywords: Appendiceal mucinous neoplasms; Appendiceal neoplasms; Low-grade appendiceal mucinous neoplasm; Low-grade appendiceal mucinous neoplasms.

Publication types

  • Multicenter Study

MeSH terms

  • Adenocarcinoma, Mucinous / diagnosis*
  • Adenocarcinoma, Mucinous / mortality
  • Adenocarcinoma, Mucinous / pathology*
  • Adenocarcinoma, Mucinous / therapy
  • Adult
  • Aged
  • Aged, 80 and over
  • Appendiceal Neoplasms / diagnosis*
  • Appendiceal Neoplasms / mortality
  • Appendiceal Neoplasms / pathology*
  • Appendiceal Neoplasms / therapy
  • Case-Control Studies
  • Female
  • Humans
  • Japan
  • Male
  • Middle Aged
  • Neoplasm Grading
  • Neoplasm Metastasis
  • Neoplasm Staging
  • Prognosis
  • Retrospective Studies
  • Survival Analysis