Mesothelioma is a very difficult disease for medical professionals to disgnose, because of the fact that it can be easily misdiagnosed as a type of carcinoma, lung cancer, or other type of illness. With further testing, mesothelioma can be classified based on the location of the tumor and also on the type of Mesothelioma cells.
Malignant mesotheliomas are then divided into four main histological subtypes based on the type of mesothelioma cells: epithelial, sarcomatous, and mixed or biphasic.
Well-Differentiated Tubulopapillary Type Mesothelioma;
Epithelial Type Mesothelioma (inlcudes tubulopapillary and nonglandular or eptheloid): In general terms the behaviour of epithelial mesotheliomas is similar to that of carcinomas with local spread, large pleural effusions, and metastases to regional lymph nodes;
Sarcomatous Type Mesothelioma (includes desmoplastic mesothelioma): Sarcomatous mesotheliomas are associated more frequntly with distant metastases, little or no effusion, and shorter survival;
Desmoplastic Mesothelioma: Among the biphasic and sarcomatous subtypes is a group of tumours in which more than 50% of the tumour consists of dense, hypocellular collagenous tissue. This is known as desmoplastic mesothelioma;
Biphasic Type Mesothelioma (or “mixed-type”): Mixed mesotheliomas have intermediate features;
Poorly Differentiated Type Mesothelioma (or “undifferentiated”).
Of these types, epitheleal type is the most common; 50% of pleural mesothelioma is of the epitheleal type, and 75% of peritoneal diffuse malignant mesotheliomas are of this type. The next two, biphasic or sarcomatous type, are equally represented types of mesothelioma; 25% in pleural mesothelioma cases and 15% in peritoneal diffuse malignant mesothelioma. The remaining percentage of cases are poorly differentiated or unclassifiable.
Medical professionals will us thoracoscopy and special stains which can be helpful in identifying the particular cellular classification. In some cases, a more thorough examination will be necessary, such as obtaining tissue samples, through a procedure called a biopsy, in which a larger sample may be re-examined.
