Accuracy of pleural biopsy using thoracoscopy for the diagnosis of histologic subtype in patients with malignant pleural mesothelioma

BACKGROUND. Promising results with trimodality therapy combining surgery, chemotherapy, and radiotherapy have been obtained in the management of patients with malignant pleural mesothelioma (MPM). However, the histologic subtype has to be taken into account because of its influence on prognosis. The aim of the current study was to analyze retrospectively the accuracy, sensitivity, and specificity of preoperative thoracoscopy for diagnosis of the histologic subtype of MPM. METHODS. The histologic reports from all consecutive patients undergoing 'intent-to-treat' surgery from 3 institutions as well as the initial pathologic diagnosis obtained using thoracoscopy were reviewed and compared after institutional review board approval. All cases of MPM were confirmed by a panel of pathologists. RESULTS. Ninety-five patients were included in the current study. Of these 95 patients, 75 underwent extrapleural pneumonectomy, 9 patients underwent pleurectomy/decortication, and 11 patients underwent pleurectomy. Of the 95 patients with a final diagnosis of MPM, 80 (84.2%) were classified as having epithelial and 15 (15.8%) as having biphasic subtype. Among the 87 patients classified as having MPM of epithelial subtype after the initial thoracoscopy, 75 cases (86.2%) were confirmed to be a true histologic diagnosis and 12 cases (13.8%) were found to be of biphasic subtype at final diagnosis. One patient with a biphasic subtype at initial thoracoscopy was found to have MPM of epithelial subtype after surgery. The sensitivity and specificity values of an epithelial subtype diagnosis after thoracoscopy were 94% and 20%, respectively, with a positive predictive value of 86% and a negative predictive value of 37%. Conversely, the sensitivity and specificity values of a biphasic subtype diagnosis after thoracoscopy were 20% and 98%, respectively, with a positive predictive value of 75% and a negative predictive value of 87%. CONCLUSIONS. Pleural biopsy performed using thoracoscopy is considered to be the cornerstone of the diagnosis and pleural staging of MPM. However, this procedure appears to be less efficient in diagnosing the histologic subtype as either epithelial or biphasic.