Pleuroscopy

Pleural effusions are common problems in pulmonary practice. The pleura has been largely ignored and not been an area of great deal of interest by pulmonologists. Beyond performing thoracentesis and closed pleural biopsy, there has been little interest in developing this field further in either basic research or diagnostic techniques. If a pleural biopsy is warranted, a physician has to choose between a closed pleural biopsy and an open surgical procedure. The closed pleural biopsy more often provides skeletal muscle rather than pleura for diagnosis. Biopsy procedures play an essential role in the diagnostic evaluation of patients with respiratory diseases. These techniques were developed during the last century, yet have been refined during last the last 2 decades. Recent advances in endoscopic technology have produced sophisticated instruments and telescopes with extremely high optimal resolution and small diameters. This has provided the capacity to perform the procedures even under local anesthesia and conscious sedation in an outpatient department. Like with all medical procedures, the risk:benefit ratio of invasive methods needs to be considered for each individual patient, weighing the risk of morbidity and mortality against the benefit of obtaining an early diagnosis to guide correct therapy. Usually, the more invasive procedures are used if simpler, minimally invasive methods have failed, if the latter are not very promising for obtaining a reliable diagnosis, or if additional therapeutic options can be combined with the diagnostic application. Pleuroscopy offers “a window to the pleura,” a procedure which was actually performed first by Jacobaeus several decades ago.1,2 This technique, which is underused, can be performed under local anesthesia and conscious sedation through only 1 or 2 ports of entry by a pulmonologist in an endoscopy suite using reusable rigid instruments.2 To avoid confusion, it has been suggested by Weissberg that the old term “pleuroscopy,” as used in 1923, should be favored over “medical thoracoscopy.”3,4 In Europe, pleuroscopy is a part of the training program in pulmonary medicine5 but has not been very popular in the United States, where according to a national survey in 1994, it was performed only by 5% of all pulmonary physicians.6 Several studies have tried to determine the diagnostic accuracy of pleuroscopy in the setting of undiagnosed pleural effusion, but the results vary widely, with a range of approximately 60% to 90%.7–10 Closer evaluation of the study designs reveals that the duration of follow up has occasionally been short or frequently not mentioned at all. One well-designed study of 102 patients reported by Menzies and Charbonneau with follow-up periods between 1 and 2 years found a sensitivity of 91%, specificity of 100%, accuracy of 96%, and negative predictive value of 93%.8 Boutin et al. reported a false-negative rate of 15% within 1 year of follow up,7 whereas Enk and Viskum reported a diagnostic accuracy of 69% with a 5-year follow-up period.9 In comparison, even in a study on thoracotomy in patients with pleural effusion of undetermined etiology after a pathologic diagnosis of a benign pleural process, 25% of patients were diagnosed with a malignancy within 6 months.10 In a study in the current issue by Janssen et al.,11 the authors provide a reaffirmation of the clinical use of a pleuroscopy. It is an elegant presentation of a long-term follow up of a common problem of exudative pleural effusion. The study also makes a solid argument for the early use pleuroscopy based on its high diagnostic accuracy. Diagnostic pleuroscopy is a valid indication in cases of exudates in which the etiology remains undetermined after pleural fluid analysis.12 The procedure allows immediate and reliable histologic diagnosis, including a high yield in tuberculosis cultures, and scope for determination of hormone receptors in some malignancies. Furthermore, staging in lung cancer and diffuse mesothelioma is possible. The exclusion of an underlying malignancy or tuberculosis is provided with high probability. Surgery, including surgical thoracoscopy, is not only much more invasive and expensive, it also does not produce any better diagnostic results than pleuroscopy and should therefore be reserved for very selected cases. Malignant pleural effusions are today the leading diagnostic and therapeutic indication for pleuroscopy.13,14 In a prospective intrapatient comparison, the diagnostic yield of nonsurgical biopsy methods in malignant pleural effusions was studied simultaneously in 208 patients, including 116 metastatic pleural effusions with 28 breast cancers, 30 cancers of various other organs, 58 of undetermined origin, 29 cancers of the lung, 58 diffuse malignant mesotheliomas, and 5 malignant lymphomas.15 The diagnostic yield was 62% by pleural fluid cytology, 44% by closed pleural biopsy, and 95% by pleuroscopy. The sensitivity of pleuroscopy was higher than that of cytology and closed pleural biopsy combined (95 vs. 74%, P > 0.001). The combined nonsurgical methods were diagnostic in 97% of malignant pleural effusions. In 6 of the 208 cases (2.8%), an underlying neoplasm was suspected at pleuroscopy but confirmed only by thoracotomy or autopsy. The reasons for false-negative results of pleuroscopy include insufficient and nonrepresentative biopsies that depend largely on the experience of the thoracoscopist and the presence of adhesions preventing access to neoplastic tissue. The diagnostic sensitivity of pleuroscopy is similar for all types of malignant effusion. As reported my Loddenkemper, the overall yield in 287 cases was 62% for pleural fluid cytology and 95% for pleuroscopy; the yield for pleural fluid cytology and pleuroscopy did not vary greatly between lung carcinomas (n = 67) with 67% versus 96%, extrathoracic primaries (n = 154) with 62% versus 95.5%, and diffuse malignant mesotheliomas (n = 66) with 58% versus 92%.2 In diffuse malignant mesothelioma, pleuroscopy can provide an earlier diagnosis and better histologic classification than closed pleural biopsy because of larger and more representative biopsies and more accurate staging. This could have important therapeutic implications, because much better responses to local immunotherapy or local chemotherapy have been observed in the early stages (I and II).16 Although the diagnostic yield of pleural fluid tuberculosis culture combined with closed needle biopsy is quite high, there could be indications for pleuroscopy in otherwise uncertain pleural effusions. The diagnostic accuracy of pleuroscopy is almost 100% because the pathologist is provided with multiple, selected biopsies and the cultural proof of tubercle bacilli growth is more frequent.2 Pleuroscopy also provides an avenue for talc poudrage, which is currently the best conservative method for pleurodesis. Unfortunately, pleuroscopy is not a widely popular procedure among pulmonologists in the United States. Most pulmonologists are not familiar with the use of the rigid thoracoscope as a result of a lack of training in most pulmonary fellowships. The semirigid pleuroscope used in this study offers a solution to some of these problems.17 The design of the instrument is similar to commonly used bronchoscopes, making it more familiar to many pulmonologists. The rigid body allows for easy steering within the pleural cavity. It has a working channel that is similar to a conventional bronchoscope, allowing the use of standard flexible biopsy forceps. It also connects to the processor and light source that are found in most bronchoscopy suites. The semirigid pleuroscope allows for the visualization of abnormal areas for direct biopsy. This prevents a common problem associated with blind pleural biopsies. The single incision to the chest that is needed for placement of the pleuroscope is not much larger than that made for the insertion of the chest tube. In addition, the pleuroscope affords a view of the significant area of the pleural cavity, allowing the physician to effectively select suspicious areas. As a word of caution, only a properly trained operator should perform these procedures, and patients need to be appropriately selected for this minimally invasive approach. The ease of use of this new instrument and its compatibility with existing bronchoscopy equipment should encourage American pulmonologists to get trained in pleuroscopy. Pleuroscopy is a safe procedure, which is even easier to learn than flexible bronchoscopy, provided sufficient experience with chest tube placement has been gained. However, like with all technical procedures, there is a learning curve before full competence is achieved. As part of the new field of interventional pulmonology, it should be included in the training program for chest physicians. The present study again validates that role of pleuroscopy in pleural effusion. Similar to the advances made in early detection and management of lung cancer with the advent of fiberoptic bronchoscope and similar to the use of bronchoalveolar lavage, which has improved our understanding related to a variety of respiratory diseases, the hope would be that pleuroscopy will also help advance our understanding, diagnostic capability, and management of pleural disease. Pulmonologists should consider learning and performing pleuroscopy to improve the welfare of our patients suffering with the very common entity of pleural effusion. Let us “open the window.”