Mesothelioma Pathology

Mesothelioma can be divided into types of localized and diffuse pathology, but the former is extremely rare. When making a diagnosis of mesothelioma, it is important to confirm the location of the tumor and the specific raw results before histological examination. 

Mesothelioma can be categorized histologically as epithelioid type, sarcomatoid type, biphasic type, desmoplastic type, among others. It can take many forms; consequently, there are many diseases to be differentiated when the pathology diagnosis of mesothelioma is based on histological analyzes.

Immunohistochemical stains are useful for diagnosis, but the right combination of antibodies as positive or negative markers should be selected and a full evaluation of the results of staining is necessary.

The accuracy of pathological diagnosis is very important for patients because they can receive official compensation or relief when the diagnosis of mesothelioma disease is confirmed. Under current conditions, clinicians and pathologists must make a concerted effort to improve the accuracy of diagnosis of mesothelioma.

Incidence of the disease of mesothelioma

The pathology of mesothelioma is a malignant tumor that originates in the pleura, peritoneum, pericardium and the tunica vaginalis, all places where a coating of normal mesothelial cells is present.

According to official data of Ministry of Health, Labour and Welfare of Japan, the number of deaths due to mesothelioma was 500 in 1995, gradually increasing to 953 in 2004.

This increase seems to parallel the increase in the amount of pathology of asbestos imported into Japan between 1960 and 1975, since the latency period from the onset of exposure to asbestos and a first diagnosis of mesothelioma is approximately 40 years.

A more detailed analysis of the 878 patients who officially died of mesothelioma in 2003 reveals that the male: female ratio was almost 3: 1 and the peak age of patients was 60 years for men and more than 70 in women.

The location mesothelioma in the pleura was in 84% of cases in the peritoneum in 12% and 1% in the pericardium; there were no cases of mesothelioma in the tunica vaginalis. A greater proportion of women had pathology mesothelioma of the peritoneum and pericardium in the pleura

Overall conclusions on mesothelioma pathology

The localized form of mesothelioma disease is diagnosed more often in the past; However, most localized forms are diagnosed today as a SFT, which is a separate mesothelioma entity based on immunohistochemical phenotype (positive for CD34, a marker of primitive endothelial cells) and has no related to exposure to asbestos.

In the early stage of pleural mesothelioma, small nodules found in the parietal pleura (not the visceral pleura) which eventually spread along the pleural surface. Eventually, show producing pleural adhesion, and tumor contains all the lung parenchyma.

Very few cases of peritoneal mesothelioma have been reported in the first stage and, consequently, little is known in terms of pathology and progression of disease during the early stage. Most peritoneal mesothelioma is a diffusely extensive serous tumor involves a large intestinal tumor or located in the omentum or mesentery.

After the initial diagnosis of mesothelioma, it is important to confirm the location of the tumor and pathology gross findings before histological examination. In the case of pleural mesothelioma, a tumor in the lung parenchyma suggests lung cancer with pleural extension.

In women with peritoneal spread, ovary should be carefully considered as the primary tumor site because the diagnosis of differential pathology between ovarian cancer and peritoneal mesothelioma is difficult and can only be performed on the basis of histological analysis .