Frozen Sections in Pleural Pathology: A Valuable Tool

Our plain-English summary of Frozen Sections in Pleural Pathology: A Valuable Tool, by G. Karpathiou, M. Froudarakis, F. Forest, et al (Respiration; International Review of Thoracic Diseases, 2017).

The study

• Authors: G. Karpathiou, M. Froudarakis, F. Forest, M. Mobarki, A. Patoir, P. Gay, J.M. Vergnon, O. Tiffet, M. Peoc'h
• Journal: Respiration; International Review of Thoracic Diseases
• Published: 2017;94(1):45-51
• Cited by: 14 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: Knowledge of pleural malignancy can lead to immediate pleurodesis during thoracoscopy. However, the accuracy of pleural frozen sections is largely unknown.

Objectives: To investigate the accuracy of frozen sections in pleural tumor pathology.

Methods: A total of 156 frozen pleural sections performed with the question of malignancy were retrospectively reviewed. The original frozen sections were compared to the permanent section slides which were considered as the gold standard. The influence of the following parameters on the frozen section response was evaluated: specimen size, clinical information, as well as the processing by a specialized pulmonary pathologist or not. The reasons of discrepancies were categorized as sampling errors or interpretation errors.

Results: Frozen sections made up 16.4% of 951 pleural biopsies performed in the same time period. Accurate diagnosis was feasible in 92.3% of the cases. There were 7 (4.5%) deferred (inconclusive) cases and 5 (3.2%) discrepant cases. Sensitivity of the method was 96.26%, specificity 97.87%, the positive predictive value was 99.04%, and the negative predictive value was 92%. There was no association between the responses given during frozen section and specimen size, clinical information, or the evaluation by a specialized pulmonary pathologist. Four of the 12 cases were sampling errors, while 8 cases were interpretation errors mostly made in the absence of fat tissue invasion. Thus, paucicellular lesions without prominent invasion - fat invasion or haphazardly invading cellular proliferation - were those posing most of the difficulties during frozen section.

Conclusions: Frozen sections are a highly accurate tool in pleural pathology. Thus, they can be used when an immediate pleurodesis is requested.

© 2017 S. Karger AG, Basel.

In plain English

This retrospective study from the University Hospital of Saint-Étienne, France, reviewed 156 frozen sections of pleural tissue from 2010 to 2016. A frozen section is a rapid slide read during thoracoscopy; each was requested to check for malignancy. The authors compared every frozen-section answer with the final diagnosis on permanent slides. Frozen sections were made for 16.4% of 951 pleural biopsies. The frozen-section answer was correct in 92.3% of cases. Seven cases (4.5%) were inconclusive, and 5 (3.2%) disagreed with the final diagnosis: 1 false positive and 4 false negatives. Excluding the 7 inconclusive cases, Table 2 gives sensitivity 96.26% (95% confidence interval 90.70 to 98.97) and specificity 97.87% (88.71 to 99.95); the results text prints slightly different figures. Answers were not associated with specimen size, clinical information, or whether a specialized pulmonary pathologist read the slide. Of 12 problem cases, 4 were sampling errors and 8 interpretation errors. Asbestos exposure was noted for 9 patients. The authors concluded that pleural frozen sections are a valuable and accurate tool. They noted the study was retrospective and had no patient follow-up.

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 study of diagnostic accuracy. Frozen-section diagnoses were compared with final permanent-section diagnoses, which served as the gold standard.
• Who was studied: 156 consecutive frozen sections of pleural tissue from 107 males and 49 females with recurrent pleural effusions, examined at the University Hospital of Saint-Étienne, France, from 2010 to 2016.
• Exposure: Not an asbestos exposure study. The test studied was the intraoperative frozen section, requested to check pleural tissue for malignancy. Asbestos exposure was mentioned in the clinical information for 9 of the 156 cases (5.8%).
• Main results:
  • Frozen sections were performed in 16.4% of the 951 pleural biopsies received in the same period.
  • An accurate frozen-section diagnosis was achieved in 92.3% of the 156 cases.
  • 7 cases (4.5%) were inconclusive (deferred) at frozen section. Permanent sections later showed malignancy in 5 of them and no malignancy in 2.
  • 5 cases (3.2%) were discrepant: 1 was called malignant on frozen section but was nonspecific pleuritis, and 4 were called nonmalignant but proved malignant.
  • Deferred cases were excluded from the diagnostic accuracy analysis. With them excluded, the discussion and Table 2 report sensitivity of 96.26% (95% CI 90.70 to 98.97) and specificity of 97.87% (95% CI 88.71 to 99.95) for detecting malignancy.
  • The results text gives different figures from Table 2: sensitivity 95.6%, specificity 97.96%, positive predictive value 98.96% and negative predictive value 92.31%. Table 2 gives a positive predictive value of 99.04% and a negative predictive value of 92.00%.
  • Frozen-section responses were not associated with specimen size (p = 0.9) or with the clinical information given (p = 0.1).
  • Responses did not differ between a specialized pulmonary pathologist (73 cases) and nonspecialized pathologists (83 cases) (p = 0.5).
  • Of the 12 deferred or discrepant cases, 4 were sampling errors and 8 were interpretation errors, mostly in the absence of fat tissue invasion.
  • 4 of the 7 deferred cases were mesotheliomas: 2 epithelioid, 1 sarcomatoid and 1 desmoplastic.
  • One of the false-negative sampling errors was a biphasic malignant pleural mesothelioma.
  • Asbestos exposure was listed in the clinical information for 9 cases (5.8%).
• The authors' conclusion: The authors concluded that pleural frozen sections are a valuable and accurate tool for diagnosing malignancy immediately, allowing pleurodesis in the same procedure. In their view, pleurodesis should be withheld when the frozen section gives no definitive answer or shows no malignancy.
• Limitations the authors state:
  • The study was retrospective, and some clinical information, such as side effects and complications of the technique, was missing.
  • Factors in reaching the frozen or final diagnosis, such as consensus after discussion, might be missing.
  • There was no patient follow-up, especially for patients with a histological diagnosis of benign pleural effusion.

Topics

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

Medical terms in this study, explained in our Lexicon: Frozen Section, Pathology, Pleurodesis, Thoracoscopy.

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