Unfortunately, medical terms can sometimes be confusing and there are often multiple names for the same condition. Pseudomyxoma peritonei (PMP) is no exception and has been classified in different ways over the years. The current classification, endorsed by the World Health Organization (WHO), is shown in the Table. It uses the term “mucinous carcinoma peritonei”, which is the same as “PMP”.
|Category||WHO grade||Typical histological features|
|1||Low-grade mucinous carcinoma peritonei||G1||Strips of mucinous cells showing relatively few abnormal features lying within abundant mucin|
|2||High-grade mucinous carcinoma peritonei||G2||High-grade features, involving at least 10% of the tumour|
|3||High-grade mucinous carcinoma peritonei with signet ring cells||G3||Signet ring cells present (signet ring cells are a type of cell associated with worse prognosis)|
Acellular mucin can occur in PMP, but also in ruptured ovarian cysts, causing it to accumulate in the peritoneal cavity. However, removing the ovarian cyst cures it. A hallmark is acellular mucin in the peritoneal cavity without epithelial cells. It is not graded.
A crash course in medical terms
If you are not familiar with the words used by doctors when describing tumours, here are some definitions:
Cannot spread to distant parts of the body
Can spread to distant parts of the body
A mass due to autonomous growth of cells, whether benign or malignant
Another word for tumour
A malignant tumour
Anything abnormal on or in the body, not just neoplasms
Neoplasms are classified according the type of normal cell they resemble. For example, adenocarcinoma is a type of cancer resembling glands (adeno = gland and carcinoma = cancer of lining cells). Tumours are called mucinous if more than 50% of the mass consists of mucin.
The pathology of pseudomyxoma peritonei and appendix tumours
Pseudomyxoma Survivor and N Carr, MB BS FRCPath FRCPA FAcadMEd, Pseudomyxoma Survivor website, 2023
A Consensus for Classification and Pathologic Reporting of Pseudomyxoma Peritonei and Associated Appendiceal Neoplasia
Carr, Norman J. FRCPath; Cecil, Thomas D. MD; Mohamed, Faheez; Sobin, Leslie H.; Sugarbaker, Paul H.; González-Moreno, Santiago MD PhD; Taflampas, Panos MD; Chapman, Sara PhD; Moran, Brendan J. MD, A Consensus for Classification and Pathologic Reporting of Pseudomyxoma Peritonei and Associated Appendiceal Neoplasia, The American Journal of Surgical Pathology: January 2016 – Volume 40 – Issue 1 – p 14-26 doi: 10.1097/PAS.0000000000000535
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Complete cytoreduction for pseudomyxoma peritonei (Sugarbaker technique)
National Institute for Health and Care Excellence (NICE) Complete cytoreduction for pseudomyxoma peritonei (Sugarbaker technique), April 2004 [Online]. Available https://www.nice.org.uk/Guidance/ipg56 [Accessed February 2018]. Under review February 2018.