Diagnostic yield of pleural fluid cytology in malignant effusions: an Australian tertiary centre experience

Our plain-English summary of Diagnostic yield of pleural fluid cytology in malignant effusions: an Australian tertiary centre experience, by P. Loveland, M. Christie, G. Hammerschlag, et al (Internal Medicine Journal, 2018).

The study

• Authors: P. Loveland, M. Christie, G. Hammerschlag, L. Irving, D. Steinfort
• Journal: Internal Medicine Journal
• Published: 2018;48(11):1318-1324
• Cited by: 48 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: Timely diagnosis of malignant pleural effusions is critical to guide prognosis and management decisions. Cytological analysis of pleural fluid has been the first-line diagnostic test for many decades, with highly variable reported sensitivities of 40-90%. Its diagnostic accuracy in modern practice in Australia needs to be understood.

Aims: To determine the diagnostic yield of pleural fluid cytology for the detection of malignant pleural effusions and to determine the aetiologies of pleural effusions at our centre.

Methods: The study involved the retrospective chart review of all pleural fluid samples submitted for cytological analysis at a tertiary referral centre in Melbourne, Australia, over a 12-month period. Aetiology of all effusions was determined, and sensitivity, specificity, negative predictive value and diagnostic accuracy for the detection of malignant pleural effusions were calculated. We also examined diagnostic yield based on tumour cell type.

Results: Of the 153 cases analysed, 61 (39.9%) were malignant. Lung cancers accounted for 44.3% of malignant effusions, followed by mesothelioma (18%), ovarian carcinoma (11.5%) and lymphoma (8.2%). The commonest single causes of a benign effusion were cardiac (16.3%) and parapneumonic (13%). Sensitivity for diagnosis of malignant effusions was 67.2% overall, but 87.9% for adenocarcinomas and only 45.5% for mesothelioma.

Conclusion: Tumour type is an important determinant of pleural fluid cytology diagnostic yield. Cytology has good sensitivity and specificity for the diagnosis of adenocarcinoma, but if another tumour type is suspected, particularly mesothelioma, clinicians should be aware of the limitations.

© 2018 Royal Australasian College of Physicians.

In plain English

This retrospective review of hospital case files covered 153 consecutive patients whose pleural fluid (fluid around the lungs) was tested for cancer cells (cytology) at a tertiary referral hospital in Melbourne, Australia, from January to December 2014. The article did not report on asbestos exposure. Sixty-one patients (39.9%) had a malignant (cancer-caused) effusion. The most common causes were lung cancer (27, 44.3%) and mesothelioma (11, 18.0%). On the first fluid sample, cytology found cancer in 41 of the 61 patients, a sensitivity of 67.2%. Sensitivity was 87.9% for adenocarcinomas of any type but only 45.5% for mesothelioma. A second sample found 5 more cases, raising overall sensitivity to 75.4%. Third and fourth samples found no new cases. Of 7 cancers diagnosed by pleural biopsy, 5 were malignant mesothelioma. The authors concluded that tumour type is an important determinant of how well cytology performs. They also concluded that, in their experience, mesothelioma needed pleural biopsy for nearly half of diagnoses. They noted as a limitation that they did not separate one-sided from two-sided effusions.

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: Retrospective review of case files (chart review) of consecutive patients at one hospital
• Who was studied: 153 consecutive patients who had pleural fluid sampled for cytology at a tertiary referral centre in Melbourne, Australia, January to December 2014; 91 (59%) male, average age 67 years
• Exposure: Not an exposure study. No asbestos or other exposure was reported. The study assessed pleural fluid cytology as a test for detecting malignant pleural effusion.
• Main results:
  • Of all 153 patients, 61 (40%) had a malignant pleural effusion
  • Among the 61 malignant effusions: lung cancer 27 (44.3%), mesothelioma 11 (18.0%), ovarian carcinoma 7 (11.5%), lymphoma 5 (8.2%), breast carcinoma 4 (6.6%)
  • On the first sample, cytology identified cancer in 41 of 61 patients with malignant effusion: sensitivity 67.2%, negative predictive value 82.1%, positive predictive value 100%, diagnostic accuracy 85.9%
  • Sensitivity was 87.9% for adenocarcinoma (33 cases) and 45.5% for mesothelioma (11 cases)
  • A second sample detected 5 more malignant effusions, one of them mesothelioma, raising overall sensitivity to 75.4% and diagnostic accuracy to 90.2%. Third and fourth samples detected no new cases.
  • Of the 15 malignant effusions diagnosed by means other than cytology, 7 were diagnosed on pleural biopsy, and 5 of those 7 were malignant mesothelioma
  • Mean fluid volume sent was 352 mL in correctly diagnosed malignant effusions and 372 mL in missed ones. The difference was not statistically significant (p = 0.9034).
• The authors' conclusion: The authors concluded that tumour type is an important determinant of how well pleural fluid cytology detects malignant effusion. They found sensitivity good for adenocarcinoma but lower for non-epithelial cancers, particularly mesothelioma, which in their experience required pleural biopsy for nearly half of diagnoses.
• Limitations the authors state:
  • The study did not distinguish one-sided (unilateral) from two-sided (bilateral) effusions
  • Many effusions at the hospital were likely never sent for cytology, so the data better reflect cases where the diagnosis was uncertain
  • The high sensitivity for non-adenocarcinoma non-small cell lung cancer rests on only 5 cases

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Fluid Cytology, Pleural Effusion, Prognosis, Lung Cancer, Mesothelioma, Carcinoma, Adenocarcinoma, Cytology.

Related studies

• Pleural fluid cytology samples in cases of suspected lung cancer: An experience from a tertiary care centre — G. Kaur, R. Nijhawan, et al. (2017)
• Investigating unilateral pleural effusions: the role of cytology — D.T. Arnold, D. De Fonseka, et al. (2018)
• The diagnostic utility of D2-40, calretinin, CK5/6, desmin and MOC-31 in the differentiation of mesothelioma from adenocarcinoma in pleural effusion cytology — T.S. Hyun, M. Barnes, et al. (2012)
• Diagnostic efficacy of electron microscopy and pleural effusion cytology for the distinction of pleural mesothelioma and lung adenocarcinoma — H. Domínguez-Malagón, A.M. Cano-Valdez, et al. (2016)
• EZH2, a unique marker of malignancy in effusion cytology — H. Jiang, R. Gupta, et al. (2014)
• Claudin-4 immunohistochemistry is highly effective in distinguishing adenocarcinoma from malignant mesothelioma in effusion cytology — V.Y. Jo, E.S. Cibas, et al. (2014)

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