Mesothelioma Cell Types
There are three main types of mesothelioma cells: epithelial, sarcomatoid and biphasic. The study of these cells is termed Mesothelioma histology - part of a larger field of Pathology. Doctors and pathologists consider cell type when creating a treatment plan because the cells respond differently to treatment.
Doctors will use cell type with mesothelioma type when determining viable treatment options and patient prognosis. Histology also helps prevent the mis-diagnosis of mesothelioma. For example, peritoneal mesothelioma (abdomen) and ovarian cancer can be difficult to differentiate and diagnose.
Pathologists will look for three different types of cells: Epithelial, Sarcomatoid and Biphasic - within tissue samples when mesothelioma is suspected . . .
Epithelioid Mesothelioma Cells
Epithelioid mesothelioma is the most common cell type and accounts for about around 70% of all mesothelioma cases. This cell type typically responds well to treatment and has a more favourable prognosis than other cell types. Patients with epithelioid mesothelioma have an average life expectancy of 12 - 24 months. Epithelioid mesothelioma is caused by asbestos exposure and can develop in the lungs (pleural), abdomen (peritoneal) or heart (pericardial).
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Sarcomatoid Mesothelioma
Sarcomatoid mesothelioma accounts for about 10 - 20% of mesothelioma cases and is considered the most difficult to treat. Sarcomatoid cells are known for aggressive growth, often leaving patients with a less favourable prognosis of around 6 months. This cell type can spread quickly to distant other organs. Sarcomatoid cells have an oblong, spindle shape so sarcomatoid mesothelioma is also referred to as spindle cell mesothelioma.
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Biphasic Mesothelioma
Biphasic mesothelioma, or mixed mesothelioma, contains both epithelial and sarcomatoid cells within the mesothelioma tumours. With both types of cells present, prognosis varies depending on which cell type is dominant. Patients with more epithelial cells will likely have a more favourable response to treatment compared to those with more sarcomatoid cells. Biphasic mesothelioma is caused by asbestos exposure and usually occurs in the pleura or abdomen.
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Rarer Mesothelioma Cell Types
Mesothelioma cells may sometimes be classified as rare subtypes of epithelial or sarcomatoid mesothelioma. Depending on the identified subtype, treatment options may be limited. Rare malignant mesothelioma cell types typically have a poor prognosis, often less than one year. However, some rare cell types may be benign and patients can live for years following diagnosis.
Rare subtypes include . . .
Benign mesothelioma
Benign or non-cancerous mesothelioma is a growth of mesothelium that does not spread (metastasize) to other parts of the body. These tumours are not usually life-threatening and can be removed with surgery. They do not usually come back, but doctors usually continue to monitor patients for new tumours just in case. There are several types of benign mesothelioma, differentiated by cell characteristics, 3 are listed below: Adenomatoid, Cystic and Papillary.
Adenomatoid mesothelioma
Adenomatoid mesothelioma is sometimes known as glandular or micro-glandular mesothelioma and is a subset of epithelial mesothelioma. Pleural, peritoneal or pericardial mesothelioma may all feature an adenomatoid growth pattern. When Adenomatoid cells are found in the peritoneum they behave as benign lesions and respond well to treatment. However if these cells are found in the pleura they could be malignant or benign.
Cystic mesothelioma
Benign cystic mesothelioma (BCM) is a rare disease that forms multi-cystic masses in the abdomen and pelvic regions. It occurs mostly in young to middle-aged women with the majority of cases associated with a history of abdominal or pelvic operation or a history of pelvic inflammatory disease. In some patients it can develop into malignant cystic mesothelioma cancer, but unlike malignant mesothelioma, the link between asbestos exposure and cystic mesothelioma is unclear.
Well-differentiated papillary mesothelioma
This is a rare epithelioid mesothelioma subtype most often seen in the abdominal cavity of female patients. Papillary tumours are usually benign, but studies have reported them turning into malignant mesothelioma over time, although the chance of this happening is unlikely. Researchers are not sure whether papillary mesothelioma is linked to asbestos exposure in fact the cause of this disease remains poorly understood.
Desmoplastic mesothelioma
The term desmoplasia refers to any type of growth of fibrous connective tissue. Desmoplastic mesothelioma is a rare subtype of sarcomatoid mesothelioma, it accounts for about 6% of asbestos related mesothelioma. A recent study found that about 88% of people diagnosed had already experienced metastases. This is typical of all types of sarcomatoid mesothelioma, which are generally more aggressive than epithelial cancers.
Deciduoid mesothelioma
Deciduoid mesothelioma, an epithelioid cell type, is different from the common variations of mesothelioma. Early studies found the Deciduoid subtype in the abdomens of young women and there was no link between this subtype and asbestos exposure. More recently, cases have involved men and older women. Around half of these were pleural, with a similar number of cases occurring in the abdomen.
Heterologous mesothelioma
This is an extremely rare subtype with only a hand-full of recorded cases but it is associated with asbestos exposure. These tumours are strange as they contain bodily tissues different from the tissues in which they form. Cell types found in tumours include cartilage, bone cells, and muscle cells. The reasons why cell types from other parts of the body end up in these tumours is not yet understood.
Lymphohistiocytoid mesothelioma
First discovered in 1988, this is one of the rarest subtypes of sarcomatoid mesothelioma with less than 1% of asbestos related cancer cases. The prognosis for this subtype is very poor with many people diagnosed after the disease has progressed. These tumours tend to have a mix of epithelioid cells and inflammatory cells and it is often mis-diagnosed as non-Hodgkin’s lymphoma or other conditions.
Small cell mesothelioma
This is an extremely rare subtype of mesothelioma and is is often misdiagnosed as small cell lung cancer. This subtype is most commonly classified as a epithelial cell type, but many tumours with small cell features are biphasic, indicating both epithelial and sarcomatoid cells.
If you would like some advise on whether you can claim for mesothelioma, please contact us on the number below and ask for Kathy or Warren.
More Mesothelioma Pages
Types of Malignant Mesothelioma. Information about the disease
Mesothelioma Symptoms - Pleural, Peritoneal and Pericardial
Mesothelioma Diagnosis, including Prognosis and Staging
Mesothelioma Treatment Options: Surgery, Radiation Therapy and Chemotherapy
Author
Kathy Cooke MA. BSc
Cancer consultant and advisor
Kathy has worked in the cancer field for over 30 years. She was course leader for the MSc in Radiotherapy and Oncology at University of Hertfordshire. Then pre-treatment radiotherapy manager at the Cromwell Hospital in London and Partnership Quality Lead for Macmillan Cancer Support.. Read more >
