Evaluation of appendiceal mucinous neoplasms with a new classification system and literature review

Abstract

Appendiceal mucinous neoplasms constitute a diagnostic spectrum ranging from adenoma to mucinous adenocarcinoma. To date, many classification systems have been proposed to reflect the histomorphological diversity of neoplasms in this range and their clinical correspondence, and also to form a common terminology between the pathologist and clinicians. The aim of this review is to provide an updated perspective on the pathological features of appendiceal mucinous neoplasms. Using the 2016 Modified Delphi Consensus Protocol (Delphi) and the Eighth Edition of the American Joint Committee on Cancer (AJCC) Cancer Staging Manual, 19 cases presented from June 2011 to December 2016 were evaluated and diagnosed with appendiceal mucinous neoplasia. According to the Delphi, non-carcinoid epithelial tumours of the appendix were categorized in eight histomorphological architectural groups. These groups are adenoma, serrated polyp, low-grade appendiceal mucinous neoplasm, high-grade appendiceal mucinous neoplasm, mucinous adenocarcinoma, poorly-differentiated adenocarcinoma with signet-ring, signet-ring cell carcinoma and adenocarcinoma. The most common symptom was right lower quadrant pain. The median age of these cases was 60±15 years. There was a preponderance of females (F/M: 15/4). In our re-evaluation, six cases were diagnosed as serrated polyp. There were 11 cases in the LAMN group and two cases in the mucinous adenocarcinoma group. Using the Delphi and the AJCC manual, there were many changes in the classification, evaluation and treatment of appendiceal mucinous neoplasms. These classification systems have facilitated the compatibility and communication of clinicians and pathologists and have guided clinicians on treatment methods.

The Utility of Routine Histopathological Examination of the Appendectomy Specimens

“…In 2018, Gündoğar et al studied 19 cases of appendiceal mucinous neoplasms revealing that the most common clinical symptoms were right lower abdominal pain (27%), abdominal mass (16%), weight loss (10%), and bowel habits change in (5%), and (61%) of their cases presented with lower abdominal pain, whereas the rest were detected incidentally. The mean age of these 19 cases was 60±15 (30-84) years 37 .…”

Rare Cases of Low-Grade Appendiceal Mucinous Neoplasm: Two Case Reports and a Literature Review

“…AM was first described in 1842 by Rokitansky and is an unspecific term used to define cystic dilation of the appendix caused by accumulation of mucus secretion. AM is a rare disease found in < 1% of all appendectomy specimens and misdiagnosed as acute appendicitis or pelvic mass or retroperitoneal tumors in many cases, because the most frequent symptom is acute or chronic right lower quadrant abdominal pain [1, 2, 3, 4]. It can be diagnosed at any age and should be considered in the differential diagnosis of acute abdominal pain at any age.…”

“…Appendiceal mucocele (AM) is a rare condition, accounting for 0.3–0.7% of appendiceal pathology, comprising 8% of appendiceal tumors, and is found in <1% of all appendectomy specimens [1, 2, 3]. It is often misdiagnosed as appendicitis, pelvic mass, or retroperitoneal tumor in many cases because the most frequent symptom is right lower quadrant abdominal pain [3, 4]. AM can be diagnosed at any age and should be considered in the differential diagnosis of abdominal pain.…”

“…AM can be diagnosed at any age and should be considered in the differential diagnosis of abdominal pain. Although there are pathological classifications, surgical resection is the accepted treatment modality for each histological type to prevent the development of peritoneal pseudomyxoma (PP) that is associated with a high mortality rate [1, 2, 3, 4]. However, preoperative diagnosis of AM is difficult because of the non-specific clinical manifestations of the disease.…”

A rare cecal subepithelial tumor in a Crohn´s Disease patient

“…Advanced stage disease may present with abdominal distension due to the accumulation of mucin in the peritoneal space, which may occur in about 20% of patients with a mucinous neoplasm of appendix. 1,2 Low-grade appendiceal mucinous neoplasms (LAMN) are the most frequent sub-group of AMNs, which are characterized by mucinous epithelial proliferation with extracellular mucin and pushing tumor margins. 3 The distinctive feature of LAMN is the low-grade cytologic atypia combined with the absence of signs that indicate invasive infiltration of the appendiceal wall.…”