Pleural fluid cytology samples in cases of suspected lung cancer: An experience from a tertiary care centre

Our plain-English summary of Pleural fluid cytology samples in cases of suspected lung cancer: An experience from a tertiary care centre, by G. Kaur, R. Nijhawan, N. Gupta, et al (Diagnostic Cytopathology, 2017).

The study

• Authors: G. Kaur, R. Nijhawan, N. Gupta, N. Singh, A. Rajwanshi
• Journal: Diagnostic Cytopathology
• Published: 2017;45(3):195-201
• Cited by: 8 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objective: Pleural effusion is present in some patients with lung carcinoma. This study was undertaken to evaluate the role of pleural fluid cytology in suspected cases of lung carcinoma.

Methods: In this prospective study, 86 cases of suspected primary lung carcinoma associated with pleural effusion were included. Cytomorphology of conventional smears was combined with LBC smears and a cytomorphological diagnosis was offered. An immunopanel of CK7, CK5/6, p63, TTF1, calretinin, and CD56 was applied on cell blocks. Additional immunochemical markers were performed based on clinical details and cytomorphology, wherever indicated.

Results: The mean age of the patients was 56.8 years. The female to male ratio was 2.1:1. Lung nodule/mass could be detected in 70.9% cases by CECT chest. Cytomorphology was evaluated in all the 86 cases and IHC was used to refine the cytomorphological diagnosis. After IHC along with clinico-radiological details, 61/86 (71%) cases were confirmed as metastasis from lung primary, 5/86 (5.8%) were diagnosed as metastatic adenocarcinoma of extrapulmonary origin, and 6/86 (7%) were metastatic SCC. A diagnosis of adenosquamous carcinoma was suspected in five cases. Other cases included small cell carcinoma (n = 2), large cell carcinoma (n = 2), large cell neuroendocrine carcinoma (n = 3), and mesothelioma (n = 1). One case remained "uncategorized" even after IHC.

Conclusions: Immunohistochemistry (IHC) performed on the pleural fluid sample can accurately diagnose and subtype primary lung carcinoma even in cases where radiology failed to identify a definite lung lesion. IHC can further help in delineating primary site in tumors of extrapulmonary origin. © 2017 Wiley Periodicals, Inc. Diagn. Cytopathol. 2017;45:195-201. © 2016 Wiley Periodicals, Inc.

© 2017 Wiley Periodicals, Inc.

In plain English

This prospective study, from the Postgraduate Institute of Medical Education and Research in Chandigarh, India, examined pleural fluid (fluid around the lungs) from 86 patients with suspected primary lung cancer seen between May 2014 and September 2015. Only patients whose preliminary pleural fluid cytology strongly suggested a carcinoma were included. The authors compared two ways of preparing fluid smears, conventional and liquid-based, and applied immunohistochemical (IHC) stains to cell blocks made from the fluid. After IHC, combined with clinical and imaging details, 61 of 86 cases (71%) were confirmed as spread from a lung primary and 5 of 86 (5.8%) as adenocarcinoma from outside the lung. Six cases (7%) were metastatic squamous cell carcinoma. One case (1.2%) was diagnosed as mesothelioma, and follow-up biopsy or needle aspiration gave the same diagnosis. This diagnostic study did not mention asbestos. It recorded smoking histories but did not examine what caused the cancers. The authors concluded that IHC on pleural fluid cell blocks gave results comparable with biopsy samples for diagnosing and subtyping lung carcinoma, even when imaging found no definite lung lesion.

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: Prospective diagnostic study of pleural fluid cytology with immunohistochemistry on cell blocks
• Who was studied: 86 patients with clinically suspected primary lung carcinoma and pleural effusion, referred for pleural fluid cytology at the Postgraduate Institute of Medical Education and Research, Chandigarh, India, May 2014 to September 2015. Only cases with a strong presumptive diagnosis of carcinoma on preliminary pleural fluid cytology were included. There were 58 males and 28 females, aged 28 to 85 years (mean 56.8).
• Exposure: Not an exposure study, and asbestos is not mentioned. The study evaluated diagnostic methods: conventional versus SurePath liquid-based smears, and an immunopanel of CK7, CK5/6, p63, TTF-1, calretinin and CD56 applied to cell blocks, with extra markers in selected cases. Smoking history was recorded but not analyzed as a cause: 45 active smokers (53.6%), 9 passive smokers (10.7%) and 30 nonsmokers (35.7%). Smoking history was not available for two patients.
• Main results:
  • After IHC, 61 of 86 cases (71%) were confirmed as metastasis from a lung primary.
  • 5 of 86 cases (5.8%) were diagnosed as metastatic adenocarcinoma from outside the lung: breast (2), pancreas (1), ovary (1) and prostate (1).
  • Six cases (7%) were metastatic squamous cell carcinoma. Adenosquamous carcinoma was entertained in 5 cases (5.8%). There were 2 small cell carcinomas, 2 cases suggestive of large cell carcinoma and 3 large cell neuroendocrine carcinomas.
  • One case (1.2%) was diagnosed as mesothelioma, and one case (1.2%) remained uncategorized after IHC. On initial cytomorphology the mesothelioma case had been called metastatic poorly differentiated carcinoma. Follow-up biopsy or FNAC also showed mesothelioma.
  • A lung lesion was detected in 39 patients (45.3%) on chest X-ray and in 61 patients (70.9%) on CECT.
  • Fluid diagnoses after IHC were compared with follow-up surgical biopsies (20 of 86 cases) and FNAC (4 of 86). All 18 fluid diagnoses of lung adenocarcinoma matched. One uncategorized case proved to be lung adenocarcinoma, and one case called adenosquamous on fluid was adenocarcinoma metastasis on biopsy or FNAC.
  • Liquid-based smears were found better than conventional smears because of greater cell concentration, less clumping and less obscuration.
  • EGFR mutation status was unknown in 39 of 86 cases. Of the remaining 47 cases, 12 had EGFR mutations, most often an exon 19 deletion.
• The authors' conclusion: The authors concluded that IHC on cell blocks from pleural fluid gave results comparable with biopsy samples for diagnosing and subtyping lung carcinoma, even when radiology failed to identify a definite lung lesion. They added that IHC can help determine the primary site in tumors from outside the lung.
• Limitations the authors state:
  • Subtype proportions found in pleural fluid do not necessarily reflect the true incidence of lung carcinoma subtypes.
  • No gold standard is available for diagnosing these cases.
  • A diagnosis of adenosquamous carcinoma is not recommended in small biopsy or cytology samples, but the authors entertained it in some cases.

Topics

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

Medical terms in this study, explained in our Lexicon: Fluid Cytology, Lung Cancer, Pleural Effusion, Carcinoma, Calretinin, Cell Block, Metastasis, Adenocarcinoma.

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