Should a cytologic study be ordered in transudative pleural effusions?

Optimal diagnostic strategies for pleural diseases and identifying high-risk patients

INTRODUCTION

Pleural diseases encompass a broad range of conditions with diverse and heterogenous etiologies. Diagnostics in pleural diseases thus represents a challenging field with a wide array of available testing to distinguish between the numerous causes of pleural disease. Nonetheless, deploying best practice diagnostics in this area is essential in reducing both duration o the investigation pathway and symptom burden.

AREAS COVERED

This article critically appraises the optimal diagnostic strategies and pathway in patients with pleural disease, reviewing the latest evidence and key practice points in achieving a treatable diagnosis in patients with pleural disease. We also cover future and novel directions that are likely to influence pleural diagnostics in the near future. PubMed was searched for articles related to pleural diagnostics (search terms below), with the date ranges including June 2012 to June 2022.

EXPERT OPINION

No single test will ever be sufficient to provide a diagnosis in pleural conditions. The key to reducing procedure burden and duration to diagnosis lies in personalizing the investigation pathway to patients and deploying tests with the highest diagnostic yield early (such as pleural biopsy in infection and malignancy). Novel biomarkers may also allow earlier diagnostic precision in the near future.

Pleural Fluid Analysis: Are Light's Criteria Still Relevant After Half a Century?

Fifty years from their initial description, Light's criteria are still unhesitatingly accepted as the default reference test for separating pleural transudates and exudates. Efforts should be focused not so much on trying to find an even more reliable technique for categorizing PEs but on improving the misclassification rate of transudates that characterize Light's criteria. Despite their shortcomings, Light's criteria may well continue their reign for another 50 years. Long live the Light's criteria!

Diagnostics in Pleural Disease

Pleural disease diagnostics represent a sprawling topic that has enjoyed a renaissance in recent years from humble beginnings. Whilst pleural patients are heterogeneous as a population and in the aetiology of the disease with which they present, we provide an overview of the typical diagnostic approach. Pleural fluid analysis is the cornerstone of the diagnostic pathway; however, it has many shortcomings. Strong cases have been made for more invasive upfront investigations, including image-guided biopsies or local anaesthetic thoracoscopy, in selected populations. Imaging can guide the diagnostic process as well as act as a vehicle to facilitate therapies, and this is never truer than with the recent advances in thoracic ultrasound.

A review of a pleural service

This paper reviews the organisation and outcomes of a pleural service, specifically geared towards the management of malignant pleural effusions, in a district general hospital in the north east of England. We summarise the evidence behind local anaesthetic thoracoscopy and indwelling pleural catheters. We then summarise the review of our service, including a discussion around complications.

Predictive models of malignant transudative pleural effusions

BACKGROUND

There are no firm recommendations when cytology should be performed in pleural transudates, since some malignant pleural effusions (MPEs) behave biochemically as transudates. The objective was to assess when would be justified to perform cytology on pleural transudates.

METHODS

Consecutive patients with transudative pleural effusion (PE) were enrolled and divided in two groups: malignant and non-MPE. Logistic regression analysis was used to estimate the probability of malignancy. Two prognostic models were considered: (I) clinical-radiological variables; and (II) combination of clinical-radiological and analytical variables. Calibration and discrimination [receiver operating characteristics (ROC) curves and area under the curve (AUC)] were performed.

RESULTS

A total of 281 pleural transudates were included: 26 malignant and 255 non-malignant. The AUC obtained with Model 1 (left PE, radiological images compatible with malignancy, absence of dyspnea, and serosanguinous appearance of the fluid), and Model 2 (the variables of Model 1 plus CEA) were 0.973 and 0.995, respectively. Although no false negatives are found in Models 1 and 2 to probabilities of 11% and 14%, respectively, by applying bootstrapping techniques to not find false negatives in 95% of other possible samples would require lowering the cut-off points for the aforementioned probabilities to 3% (Model 1) and 4% (Model 2), respectively. The false positive results are 32 (Model 1) and 18 (Model 2), with no false negatives.

CONCLUSIONS

The applied models have a high discriminative ability to predict when a transudative PE may be of neoplastic origin, being superior to adding an analytical variable to the clinic-radiological variables.

Delayed onset of benign pleural effusion following concurrent chemoradiotherapy for inoperable non-small-cell lung cancer

Chronic benign pleural effusion (BPE) is a rare complication of concurrent chemoradiotherapy (CRT) for inoperable stage IIIA non-small-cell lung cancer (NSCLC). This report presents three cases of BPE, the workup to differentiate this benign condition from recurrence of cancer and recommends a pleural biopsy as part of the diagnostic process. These inflammatory exudates often remain indolent, and may not require drainage or surgical intervention. In the absence of clinical, radiological and pathological evidence of recurrent disease, we recommend clinicians manage these patients expectantly, using regular clinical assessment and imaging.

The role of vascular endothelial growth factor in the pathogenesis, diagnosis and treatment of malignant pleural effusion

Malignant pleural effusions (MPEs) are a significant source of cancer-related morbidity. Over 150,000 patients in the United States suffer from breathlessness and diminished quality of life due to MPE each year. Current management strategies are of mostly palliative value and focus on symptom control; they do not address the pathobiology of the effusion, nor do they improve survival. Further elucidation of the pathophysiological mechanisms, coupled with the development of novel treatments such as intrapleural chemotherapeutics targeting this process, has the potential to greatly improve the efficacy of our current management options. Vascular endothelial growth factor-A (VEGF-A) has been implicated as a critical cytokine in the formation of malignant pleural effusions. Elevated levels of VEGF produced by tumor cells, mesothelial cells, and infiltrating immune cells result in increased vascular permeability, cancer cell transmigration, and angiogenesis. Therefore antiangiogenic therapies such as Bevacizumab, a monoclonal antibody targeting VEGF-A, may have a potential role in the management of malignant pleural effusions. Herein we review the pathogenesis and potential treatment strategies of malignant pleural effusions, with a focus on angiogenesis and antiangiogenic therapeutics.

An Unusual Transudative Pleural Effusion Succeeded by Pulmonary and Brain Edema and Death

Here we report a 22-year old woman with massive and bilateral transudative effusion succeeded by pulmonary edema and brain edema and death. Investigations for systemic disorders were negative. Exacerbation of dyspnea after intravenous fluid infusion was a main problem. As effusion was refractory to medical treatment, the patient was referred for surgical pleurodesis and bilateral surgical pleurodesis were done separately. Postsurgically, dyspnea exacerbation occurred after each common cold infection. Vertigo and high intracranial pressure were also a problem postsurgically. CSF pressure was 225 mm/H₂O. Therapeutic lumbar puncture was done in two sequential weeks, and the patient was on acetazolamide 250 mg/trivise a day. Despite the medical treatment, progressive dyspnea, headache, and high intracranial pressure followed by death nine months after pleurodesis. As there is a gradient of pressure between pleura and CSF, after pleurodesis brain edema must be a consequence of inversing this gradient. In conclusion, when there are any abnormalities about fluid volume or pressure in any of these cavities, we have to study other cavities.

Management of malignant pleural effusions

Malignant pleural effusions are a common clinical problem in patients with primary thoracic malignancy and metastatic malignancy to the thorax. Symptoms can be debilitating and can impair tolerance of anticancer therapy. This article presents a comprehensive review of pharmaceutical and nonpharmaceutical approaches to the management of malignant pleural effusion, and a novel algorithm for management based on patients' performance status.

Medical thoracoscopy

PURPOSE OF REVIEW

The technique and clinical applications of medical thoracoscopy have substantially evolved in the last few decades. The recent development of a semirigid thoracoscope, which is handled similarly to a bronchoscope, has made this procedure more attractive to pulmonologists. We will review the latest data on clinical applications, recently developed techniques, and safety of medical thoracoscopy, focusing mainly on its role in thoracic malignancies.

RECENT FINDINGS

Recent data confirm the high diagnostic yield of medical thoracoscopy - both with rigid and semirigid instruments - in detecting pleural metastases and determining the origin of pleural effusions. The degree of pleural adhesions found during thoracoscopy has been proposed by some authors as a prognostic factor for survival in patients with malignant pleural effusion. A large prospective multicenter study has established the safety of talc poudrage with large-particle talc, showing no cases of acute respiratory distress syndrome.

SUMMARY

Medical thoracoscopy is an excellent tool to establish diagnosis in patients with exudative pleural effusion of unclear origin. It is highly valuable in clarifying the origin of pleural effusions in patients with lung cancer, as the presence of a malignant pleural effusion is associated with poor survival and precludes the possibility of treatment with curative intention. Pleurodesis with talc poudrage is efficacious and well tolerated, especially with the use of large-particle talc.

Transudates in Malignancy: Still a Role for Pleural Fluid

Introduction: The aims of this study were to determine the distribution of transudates and exudates among pathologically proven malignant pleural effusions, and to demonstrate the necessity for cytologic studies in patients with a transudative effusion. Materials and Methods: This study is a retrospective review of all subjects diagnosed with malignant or paramalignant pleural effusion over a 10-year period at a tertiary hospital. The study included 67 subjects with malignant mesothelioma, 45 subjects with metastatic disease, and 36 subjects with paramalignant effusions. Results: There were 55 female and 93 male subjects; the mean age of the sample was 62 years. Malignant pleural effusions were transudative in 1.5% of malignant mesotheliomas, 6.8% of metastatic diseases, and 11.1% of paramalignant effusions. Conclusions: Cytological examination of pleural fluid in patients with unexplained transudative effusion is essential to rule out malignant processes. Key words: Biochemical criteria, Pleural malignancy, Pleural neoplasms

Diagnosis and management of malignant pleural effusions

Malignant pleural effusions (MPEs) complicate the clinical course of patients with a broad array of malignancies, which are most often due to lymphomas or carcinomas of the breast, lung, gastrointestinal tract or ovaries. Patients may present with a MPE as the initial manifestation of a cancer or develop an effusion during the advanced phases of a known malignancy. In either circumstance, the median survival after presentation with a MPE is 4 months. Effusions may result from direct pleural invasion (MPE) or indirect effects (paraneoplastic effusions), such as impairment of fluid efflux from the pleural space by lymphatic obstruction or pleural effects of cancer radiation or drug therapy. Because only 50% of patients with cancer who develop a pleural effusion during their clinical course have a MPE, careful evaluation of the effusion to establish its aetiology is required to direct therapy. Management is palliative with interventions directed towards decreasing the volume of intrapleural fluid and the severity of associated symptoms.

Recent advances in the diagnosis and management of malignant pleural effusions

Malignant pleural effusions (MPEs) are an important complication for patients with intrathoracic and extrathoracic malignancies. Median survival after diagnosis of an MPE is 4 months. Patients can present with an MPE as a complication of far-advanced cancer or as the initial manifestation of an underlying malignancy. Common cancer types causing MPEs include lymphomas, mesotheliomas, and carcinomas of the breast, lung, gastrointestinal tract, and ovaries. However, almost all tumor types have been reported to cause MPEs. New imaging modalities assist the evaluation of patients with a suspected MPE; however, positive cytologic or tissue confirmation of malignant cells is necessary to establish a diagnosis. Even in the presence of known malignancy, up to 50% of pleural effusions are benign, underscoring the importance of a firm diagnosis to guide therapy. Rapidly evolving interventional and histopathologic techniques have improved the diagnostic yield of standard cytology and biopsy. Management of an MPE remains palliative; it is critical that the appropriate management approach is chosen on the basis of available expertise and the patient's clinical status. This review summarizes the pathogenesis, diagnosis, and management of MPE. Studies in the English language were identified by searching the MEDLINE database (1980-2007) using the search terms pleura, pleural, malignant, pleurodesis, and thoracoscopy.

[Diagnostic keys in conventional serous fluid cytopathology]

Cells from serous effusions can easily be concentrated by centrifugation. Thereafter, various procedures allow cells to be deposited on glass slides. Standard stains give excellent morphologic details for analysis. However, unsatisfactory specimens are frequently observed in daily practice. Standardization brought by liquid based cytology may be of some help for immunocytochemistry, but conventional methods remain essential. Several decades of experience and analysis of literature allow the authors to select the best criteria for interpretation, with emphasis on the differential diagnosis of malignant vs. benign effusions.

What is the clinical significance of transudative malignant pleural effusion?

BACKGROUND

A few reports of transudative malignant effusion on a small number of patients have suggested the need to perform routine cytologic examination in all cases of transudative pleural effusion, whether encountered for malignancy or not. The purpose of this study was to investigate whether cytologic examination should be performed in all cases of transudative pleural effusion for the diagnosis of malignancy.

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 medical records, results of transthoracic echocardiography, fiberoptic bronchoscopy, chest X-ray, chest CT scan, and ultrasonogram of the abdomen. These data were examined with particular attention to identifying whether or not the malignancy was suggested on chest X-ray, examining the involvement of the superior vena cava, great vessels, and lymph nodes, determining the presence of pericardial effusion, and observing the endobronchial obstruction.

RESULTS

Transudative malignant pleural effusion was observed in seven (3.1%) of the 229 patients, and was caused either by the malignancy itself (6 patients) or by coexisting cardiac diseases (1 patient). All the patients showed evidence suggesting the presence of malignancy at the time of initial thoracentesis, which facilitated the decision of most clinicians on whether to perform cytologic examination for the diagnosis of malignancy.

CONCLUSION

Therefore, in all cases of transudative pleaural effusion, no clinical implications indicating malignancy were found on cytologic examination.