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Incidence and Histologic Subtypes

Added 06 March 2013

Cancer of the appendix is rare, accounting for about 1% of all colorectal tumours, or less than 1000 cancers a year across Canada. Cancer of the appendix is typically classified by the type of cells found within the ​tumour. Roughly half of all appendix cancers are neuroendocrine or carcinoid tumours and are discussed in the “Neuroendoc​rine” section. The remaining tumour types largely arise from epithelial cells and are classified as follows:

  • Mucinous cystadenoma and cystadenocarcinoma
  • Goblet cell carcinoma (adenocarcinoid)
  • Adenocarcinoma, which are divided into three subtypes
    • mucinous
    • colonic-type
    • signet ring

Pseudomyxoma Peritonei (PMP)

PMP is a term used to describe the clinical syndrome that arises from perforation of an appendiceal tumour and subsequent seeding of tumour cells within the peritoneal cavity. Though it has been used to describe intraperitoneal mucinous dissemination from various tumours in the appendix, and other organs, it was originally intended to describe disease that stemmed from a cystadenoma of the appendix only.

PMP should be limited to the description of more indolent disease processes associated with mucinous carcinomatosis.

Although consistency is lacking in the literature with regards to the use of terms such as disseminated peritoneal adenomucinosus (DPAM) and peritoneal mucinous carcinomatosis (PMCA), some centres use a simpler scheme separating cases in low grade appendicial mucinous neoplasms (LAMN) and high grade mucinous adenocarcinoma (MACA). This is more useful terminology as it reflects the expect behaviour of these tumour which may help guide management.

SOURCE: Incidence and Histologic Subtypes ( )
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