A malignant pleural effusion is diagnosed when exfoliated malignant cells are found in pleural fluid or when malignant cells are visualized in pleural tissue obtained by percutaneous pleural biopsy, thoracoscopy, thoracotomy, or at autopsy. Some patients with malignancy have cytology-negative pleural effusions and no direct pleural involvement with tumor. If no other cause for these effusions can be found, I term them paramalignant(Table 1).<sup>80Sahn S.A. Malignant pleural effusions Pulmonary Diseases and Disorders New York: McGraw-Hill (1998).  1429-1438

Cliquez ici pour aller à la section Références</sup> Lymphatic obstruction is an important cause of a paramalignant effusion and probably is necessary for the accumulation of a large volume of fluid in malignancy.<sup>16Chernow B., Sahn S.A. Carcinomatous involvement of the pleura: An analysis of 96 patients Am J Med 1977 ;  63 : 695 [cross-ref]

Cliquez ici pour aller à la section Références, 60Meyer P.C. Metastatic carcinoma of the pleura Thorax 1966 ;  21 : 437 [cross-ref]

Cliquez ici pour aller à la section Références</sup> Other local effects of the tumor causing a paramalignant effusion are bronchial obstruction (usually caused by squamous cell lung cancer) resulting in either pneumonia and parapneumonic effusion, atelectasis with transudative fluid, or, less commonly, a trapped lung. Effusions also can result from systemic effects of the tumor and adverse effects of therapy. In addition, pleural fluid can result from concurrent diseases unrelated to malignancy, such as congestive heart failure and nonobstructive pneumonia.

Establishing the diagnosis of a malignant pleural effusion from lung cancer signals incurability. A malignant effusion from a nonlung primarily is a manifestation of far-advanced disease and is associated with limited survival.<sup>82Sahn S.A. The pleura. State of the art American Review of Respiratory Disease 1988 ;  138 : 184

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