The diagnostic yield of pleural fluid cytology in malignant pleural effusions

The development of a pleural effusion in a patient with a known malignancy often raises the possibility that the effusion is due to malignant involvement of the pleura. Accurate diagnosis of the cause of the pleural effusion in such a patient is essential as the treatment and prognosis may vary. Currently, thoracentesis and cytologic analysis of pleural fluid cytology is usually the initial diagnostic step.

To assess the diagnostic yield of pleural fluid cytologic examination in patients with suspected malignant pleural effusions seen at our centre.

Retrospective review of the results of pleural fluid cytologic examination performed on 103 patients who presented with suspected malignant pleural effusions.

The underlying malignancies in these patients were as follows: bronchogenic carcinoma (51.5%), breast carcinoma (29.1%), hepatocellular carcinoma (1.9%), carcinoma of the stomach (1.9%), malignant mesothelioma, nasopharyngeal carcinoma, renal cell carcinoma, carcinoma of the oesophagus, lymphoma, carcinoma of the colon (1% each), unknown (9.7%). Initial pleural fluid cytology was positive for malignancy in 48.5% of patients. The yield of this diagnostic procedure was improved with repeated pleural fluid cytologic specimens and when combined with a percutaneous pleural biopsy. There was no statistically significant difference in the clinical features and pleural fluid characteristics of patients with malignant pleural effusions and those in whom the pleural effusions were paramalignant.

Pleural fluid cytologic examination is a useful initial step in the diagnostic work-up of patients with suspected malignant pleural effusions. The diagnostic yield of such examination is improved with repeated pleural fluid cytologic specimens and when combined with a percutaneous pleural biopsy. Clinical presentation and pleural fluid characteristics were inadequate in differentiating between malignant and paramalignant effusions.