A pleural effusion is a build-up of serous fluid in the spaces between the lungs and the chest wall and is the most common symptom of pleural mesothelioma. It can, however, be caused by a variety of other conditions, both benign and malignant, so an accurate diagnosis is essential for determining proper treatment. In many cases, a diagnosis is rendered based on cytological analysis of fluid smears and not by fine needle aspiration or surgical biopsy.

Introduction to the Study

Researchers in Italy conducted a study looking at the overall accuracy of cytological analysis to determine (a) whether the effusion was a benign or a malignant condition, and (b) if the effusion was malignant, could cytology then differentially indicate mesothelioma from another disorder, such as lung andenocarcinoma?

To complete this study, the researchers collected forty-five fluid smears of patients with previously-determined diagnoses, verified with immunohistochemical and pathological analysis. 14 of these smears represented a diagnosis of a benign effusion, 14 represented a metastatic invasion of the pleura from a distant cancer and 17 indicated malignant pleural mesothelioma. They enrolled seventeen doctors to interpret the results: nine were considered pathology experts and eight were pathology residents. They were instructed to determine if the smear indicated a benign or a malignant condition, and then, if the condition was malignant, to indicate if the malignancy was a primary mesothelioma or another metastatic cancer. After a period of five months, the nine experts re-evaluated their original results, but with the identification information stripped from those cases so they had to re-examine their own findings without reference to their original conclusions.

Results

The pathology experts had the highest overall accuracy rate for diagnosing a benign condition from a malignant one. They were able to accurately make the determination in more than 80% of the cases. Residents were able to make the diagnosis in about 71% of the cases. While inaccuracies did occur, the overall results for both figures indicate that cytological analysis of fluid smears is acceptable for a differentiation between benign conditions and malignant ones. However, the same cannot be said for its ability to differentiate between individual malignancies. When the doctors were asked to determine if the cancer was a primary mesothelioma or was cancer metastatic from a distant location, they were unable to do so with clinical accuracy. The experts again scored higher than the residents, but the overall results were still low for diagnostic purposes.

Conclusion

The researchers have concluded that their study establishes that cytological analysis alone is able to differentiate between a malignancy and a benign condition, but that further specification is impossible using this method. To be able to differentiate between primary malignancies, a doctor should employ a fine needle aspiration or a tissue biopsy.

Labels: mesothelioma