In this study, the investigators analyzed the efficiencies of hyaluronan, osteopontin, C-ERC/mesothelin, N-ERC/mesothelin and syndecan-1 serum levels, both individually and in combination, in distinguishing malignant pleural mesothelioma patients from patients with metastatic malignant pleural diseases, benign pleural diseases, and benign asbestos pleurisy.

In the year 2002, a database for the pleural diseases was constructed to be prospectively filled in the department. The findings, outcome features and characteristics of follow-up for all cases with pleural diseases have been recorded in this database. The patient data, including epidemiological characteristics, smoking status, history of other diseases and co-morbid conditions, previous asbestos exposure, medications and additional physical and radiological examination findings, including computed tomography scans, both serum and pleural fluid laboratory investigational data and indications of invasive procedures, were recorded in the database mentioned above. The methods employed in the diagnosis of patients; any complications; characteristics such as the stages of diseases, treatments, and course of treatments; and results were also recorded in the database. From the date of the first database establishment, a "tissue, blood, serum, and fluid specimen bank" was constructed; tissue, blood, serum and pleural fluid samples of patients, which had been taken at the beginning of diagnosis process, were stored in this bank at -80°C. The blood, serum, and pleural fluid samples of patients were stored during the diagnosis process, and if conducted, pleural tissue samples taken during invasive procedures were also stocked.

Inclusion Criteria:

• Patients with a definite pleural diseases
• Age more than 18 year-old, less than 85 year-old.
• Willingness to participate in the study.

Exclusion Criteria:

• Patients with undiagnosed pleural diseases.
• Age less than 18 year-old or more than 85 year-old.

Patients with pleural diseases; mesothelioma, metastatic malignant pleural diseases, benign pleural diseases and benign asbestos pleurisy.