The diagnosis of pleural effusions

Our plain-English summary of The diagnosis of pleural effusions, by J.M. Porcel, M. Azzopardi, C.F. Koegelenberg, et al (Expert Review of Respiratory Medicine, 2015).

The study

• Authors: J.M. Porcel, M. Azzopardi, C.F. Koegelenberg, F. Maldonado, N.M. Rahman, Y.C. Lee
• Journal: Expert Review of Respiratory Medicine
• Published: 2015;9(6):801-15
• Type of article: Review
• Cited by: 72 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Pleural effusions arise from a variety of systemic, inflammatory, infectious and malignant conditions. Their precise etiological diagnosis depends on a combination of medical history, physical examination, imaging tests and pertinent pleural fluid analyses; including specific biomarkers (e.g., natriuretic peptides for heart failure, adenosine deaminase for tuberculosis, or mesothelin for mesothelioma). Invasive procedures, such as pleuroscopic biopsies, may be required for persistently symptomatic effusions which remain undiagnosed after the analysis of one or more pleural fluid samples. However, whenever parietal pleural nodularity or thickening exist, image-guided biopsies should first be attempted. This review addresses the current diagnostic approach to pleural effusions secondary to heart failure, pneumonia, cancer, tuberculosis and other less frequent conditions.

In plain English

This article is a review and reported no new research of its own. It summarised published evidence on diagnosing the causes of fluid around the lungs (pleural effusions), including heart failure, liver disease, cancer, pneumonia and tuberculosis. It said a raised pleural fluid mesothelin level, without kidney impairment, strongly suggests pleural cancer, most commonly mesothelioma. A mesothelin cut-off above 20 nmol/L was listed with 70% sensitivity and nearly 90% specificity for distinguishing mesothelioma from other effusions. Citing earlier work, it reported that checking the fluid for cancer cells has a low yield in mesothelioma and squamous cell lung cancer (25–30%), though experienced cytologists have exceeded 70% for mesothelioma. Thoracoscopic biopsy was reported to give false negatives in about 10% of cases, most commonly in mesothelioma. Benign asbestos pleural effusion was listed among causes without specific fluid or tissue findings, requiring other causes to be excluded. The authors noted that significant exposure to carcinogens such as asbestos is an important consideration in unexplained effusions. They concluded that mesothelioma and benign asbestos pleuritis may go unnoticed unless doctors have a high index of suspicion.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Narrative review of published literature (no original data)
• Who was studied: No study population of its own; the review covered published evidence on patients with pleural effusions from heart failure, pneumonia, cancer, tuberculosis and less frequent conditions
• Exposure: Not an exposure study; asbestos is mentioned as an important consideration (significant exposure to carcinogens) when evaluating undiagnosed effusions, and benign asbestos pleural effusion is listed as a cause
• Main results:
  • Citing earlier work, the review stated that a raised pleural fluid mesothelin level (without kidney impairment) is highly suggestive of pleural malignancy, most commonly mesothelioma but also other cancers (especially ovarian and pancreatic)
  • In the review's table of pleural fluid tests, mesothelin above 20 nmol/L was listed with 70% sensitivity and nearly 90% specificity for discriminating mesothelioma from other effusions
  • Citing earlier work, the review reported that pleural fluid cytology has moderate sensitivity overall (60%) and a low yield (25–30%) in mesothelioma or squamous cell lung cancer
  • Citing a 20-year audit, the review stated that in experienced hands cytology can achieve diagnostic yields above 70% even for mesothelioma
  • The review stated that thoracoscopy gives false negatives in about 10% of cases, most commonly in mesothelioma patients
  • Citing several series, the review stated that mesothelioma is the most common cause of false-negative thoracoscopic biopsies reported as non-specific pleuritis
  • In the review's table, benign asbestos pleural effusion was listed among conditions where pleural fluid and tissue changes are not specific and other causes must be excluded
• The authors' conclusion: The authors concluded that certain causes, including mesothelioma and benign asbestos pleuritis, may go unnoticed or be hard to diagnose without a high index of suspicion. They added that a finding of non-specific pleuritis on biopsy is not always reassuring, because a small percentage of patients later turn out to have mesothelioma.
• Limitations the authors state:
  • The authors noted that few evidence-based guidelines exist and that good-quality randomized controlled studies are lacking
  • The authors stated that no data exist to guide how often and for how long undiagnosed effusions should be followed up

Topics

The National Library of Medicine indexes this study under subjects our site covers: Pleural plaques and thickening.

Medical terms in this study, explained in our Lexicon: Pleural Effusion, Biomarker, Mesothelin, Mesothelioma.

Related studies

• Natriuretic peptides in pleural effusions: Beyond a diagnosis of heart failure — J.M. Porcel (2020)
• Medical thoracoscopy vs CT scan-guided Abrams pleural needle biopsy for diagnosis of patients with pleural effusions: a randomized, controlled trial — M. Metintas, G. Ak, et al. (2010)
• A combination of MTAP and BAP1 immunohistochemistry in pleural effusion cytology for the diagnosis of mesothelioma — Y. Kinoshita, T. Hida, et al. (2018)
• Usefulness of Claudin 4 in the cytological diagnosis of serosal effusions — S. Lonardi, C. Manera, et al. (2011)
• Benign asbestos pleural effusion: diagnosis and course — B.W. Robinson, A.W. Musk (1981)
• Thoracoscopy in the early diagnosis of malignant pleural effusions — C. Boutin, P. Cargnino, et al. (1980)

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