In this article, we will discuss Malignant Pleural Mesothelioma (Detailed Diagnosis Part-I). So, let’s get started.
Malignant Pleural Mesothelioma (Diagnosis Part-I)
Pleural Fluid Studies
Thoracocentesis can provide data suggestive of mesothelioma, but rarely diagnostic: high levels of hyaluronic acid (>100 000 ng/ml) are highly indicative of malignant pleural
mesothelioma. Elevated hyaluronic acid also has good prognostic values, with higher levels being associated with better survival.
Adenosine deaminase (ADA) levels may be raised in mesothelioma patients, but before they are labeled as ADA false positives, it should be remembered that malignant mesothelioma may sometimes coexist with tuberculous pleurisy, so a culture for Mycobacterium tuberculosis is recommended in these cases.
Pleural fluid cytology may reveal mesothelioma, but it is often difficult to distinguish between benign and malignant mesothelial hyperplasia. This test is also unable to determine the invasive character of the tumor, currently considered an essential feature for a definitive diagnosis). However, in some exceptional cases, cytology may be combined with imaging techniques for the evaluation of extrapleural invasion.
Immunocytochemical and immunohistochemical techniques are also essential for differentiating between mesothelioma and metastatic adenocarcinoma in the pleura, and require biopsy tissue or paraffin-embedded
preparation of the cell button after centrifugation of a sufficient volume of pleural fluid (>100 ml). A diagnosis of mesothelioma can be reliably made when all the following conditions are found: atypical mesothelial proliferation in the pleural fluid + cell block immunohistochemistry consistent with mesothelioma + diffuse pleural thickening with nodularity + absence of any intra- or extrapulmonary mass suggestive of another primary tumor.
However, a diagnosis of malignant mesothelioma generally has legal implications. Therefore, when surgery is proposed an attempt should always be made to obtain sufficient tissue specimens for more accurate tumor typing.