What is the Clinical Significance of a Transudative Malignant Pleural Effusion

초록

Background: Recently there have been a few reports with a small number of patients indicating that transudative effusion may be observed in malignant pleural effusion and suggesting the need to perform routine cytologic examination in all cases of transudative pleural effusion, whether encountered for malignancy or not. Objectives: This study investigated the incidence, clinical presentation, and clinical significance of a transudative malignant pleural effusion. Methods: We performed a retrospective study of 229 consecutive patients with malignant pleural effusion, proven either cytologically or with biopsy. In patients with transudative pleural effusion, we reviewed the medical records, results from transthoracic echocardiography, fiberoptic bronchoscopy, and the following radiologic studies: chest X-ray, chest CT scan and ultrasonogram of abdomen. These data were examined with regards to the following issues: whether the malignancy was suggested on chest X-ray or had already been diagnosed; the involvement of the superior vena cava, great vessels and lymph nodes; the presence of pericardial effusion; and the observation of endobronchial obstruction. Results: Transudative malignant pleural effusion was observed in nine (3.9%) of the 229 patients, and was caused either by the malignancy itself (seven patients) or coexisting cardiac diseases (two patients). Primary disease of transudative pleural effusion was as following: lung cancer(seven patients), bladder carcinoma(one patient) and invasive thymoma(one patient). All patients presented evidence suggesting the presence of malignancy, allowing most clinicians to decide easily whether the cytologic examination should be performed for diagnosis of malignancy. Conclusions: Incidence of transudative malignant pleural effusion in our series was 3.9%. No clinical implications were found for the performance of cytologic examination for the diagnosis of malignancy in all cases of transudative pleural effusion.