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Pathologist


What is Malignant Mesothelioma Cancer?

Malignant mesothelioma cancer is a rare form of cancer that disrupts the mesothelial cells of the serous membranes. The most common type of mesothelioma cancer, known as pleural mesothelioma, affects the lining of the lungs. Approximately 3,000 cases of malignant mesothelioma cancer are diagnosed each year. 

Malignant mesothelioma cancer affects the membranes or lining of certain large cavities in the human body. These cavities, known as serous cavities, protect a number of vital organs in the body, including the lungs, the heart and others. The membranes that surround these cavities protect these organs from abrasions and friction that take place as the organs move against each other during typical daily movement, such as breathing. These membranes derive from specialized cells referred to as mesothelial cells, which form to create the mesothelium—the primary tissue lawyer of the serous membranes. 

Malignant mesothelioma cancer comes in three types:

Pericardial Mesothelioma Cancer: Takes place in the pericardium (lining of tissue surrounding the heart).

Peritoneal Mesothelioma Cancer: Occurs in the peritoneum (membrane surrounding the abdomen). An infrequent form of this cancer may also affect the male testicles (the lining surrounding the scrotum is an extension of the peritoneum). 

Pleural Mesothelioma Caner: As stated above, this form of mesothelioma is the most common type of mesothelioma cancer. Pleural mesothelioma cancer disrupts the lining of the lung cavity. 

All forms of mesothelioma cancer derive from a localized tumor. The disease quickly spreads to surrounding organs and tissue. The bulk of mesothelioma cases are associated with a previous exposure to asbestos fibers. That being said, not everyone who is in perpetual contact with asbestos fibers will form mesothelioma cancer. 

Although malignant mesothelioma cancer is rare, it is extremely deadly. When detected, mesothelioma cancer is often in its advanced stages, so prognosis for mesothelioma patients is not nearly as good for patients with other types of cancer that can be detected earlier. The average survival time after mesothelioma is detected is only 1 to 2 years. This timeframe; however, is dependent on the type of mesothelioma cancer that is detected. 

Mesothelioma is often difficult to accurately diagnose because the symptoms are slow-developing—a mesothelioma patient will not observe noticeable symptoms for 10-15 years following infection. Moreover, complications associated with diagnosis stem from the cellular makeup of the cancer—mesothelioma cancer is nearly impossible to differentiate from more basic cancers. That being said, numerous improvements are being made to detect the cancer in its earliest stages. 

Pathology of Malignant Mesothelioma:

Malignant mesothelioma forms from a malignant tumor that arises from the mesothelial surfaces of the peritoneal and pleural cavities. Approximately 80 percent of all mesothelioma cases originate in the pleural cavities. 

A number of factors have made the diagnosis of malignant mesothelioma cancer particularly challenging for practicing pathologists. This difficulty stems from three basic findings:

• Malignant mesothelioma cancer is exceedingly rare. 

• In the bulk of mesothelioma cases, the cancer is limited to specific tissues. In addition to being highly acute, these tissues, because of location within the body, are often difficult to observe or collect for evaluation. The use of video-assisted equipment and biopsies has greatly improved the ability to collect samples for evaluation; however, detection of the disease still remains exceedingly difficult. 

• Malignant mesothelioma cancer varies with regards to histologic appearance. Additionally, the majority of mesothelioma cases will mimic other cancerous tumors, either originating in metastatic form or within the thorax. 

Pathological Findings for Mesothelioma Cancer:

Malignant mesothelioma cancer may be categorized as epithelioid, biphasic or sarcomatoid; the categorization of the cancer is dependent on the tissue samples collected during a biopsy. Pathological diagnosis of mesothelioma cancer is achieved with the aid of immunohistochemistry to reveal the cancer and define as one of the aforementioned types. Optimal yields regarding accuracy of detection of mesothelioma cancer is typically obtained by initiating a thoracoscopic or open pleural biopsy. 

Currently, there is no singular immunhistochemical mesothelioma cancer marker to facilitate a 100% diagnosis. Hence, several mesothelial markers have been developed. In general, mesothelioma pathology begins with distinguishing between a malignant pleural process from an inflamed one. 

Rendering a distinction between malignant mesothelioma cancer and other cancers is difficult because mesothelioma cancer possesses traits similar to more generic tumors. Even as such, immunohistochemistry helps achieve an appropriate differentiation of malignant mesothelioma cancer. 

Rendering an early detection of malignant mesothelioma cancer is exceedingly difficult due to the time difference that exists between exposure and onset of the cancer. Currently, a potential use of serum markers is being evaluated for achieving accurate mesothelioma diagnosis. Ideal serum markers are ones that offer the following benefits:

• Accurate identification of various sub-types

• Early Detection

• The ability to differentiate between malignant mesothelioma cancer and benign pleural diseases, as well as other metastatic pleural malignancies. 

• The ability to record the patient’s response to administered therapy as to predict survival percentages. 

Although no serum marker is currently available, studies suggest using mesothelin or osteopontin are possible solutions. 

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