Pathology of the pleura: what the pulmonologists need to know

Our plain-English summary of Pathology of the pleura: what the pulmonologists need to know, by P.T. Cagle, T.C. Allen (Respirology, 2011).

The study

• Authors: P.T. Cagle, T.C. Allen
• Journal: Respirology
• Published: 2011;16(3):430-8
• Type of article: Review
• Cited by: 21 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Primary and metastatic pleural neoplasms, and non-neoplastic pleural diseases, can have similar clinical, radiographic and gross features. However, treatments and prognoses of these diverse pleural conditions vary greatly. Accurate diagnosis of pleural disease is therefore extremely important, and histological interpretation of pleural biopsies is vital to rendering an accurate diagnosis. Smaller biopsies contribute to the difficulties in accurately characterizing pleural lesions, and immunostains are frequently employed in their assessment. Diffuse malignant mesothelioma, the most common primary pulmonary neoplasm, is rare; however, other less common primary pleural neoplasms, including solitary fibrous tumour, the most common benign primary pleural neoplasm, occur. These neoplasms are discussed. Also, non-neoplastic pleural diseases, including granulomatous pleuritis, eosinophilic pleuritis and fibrous and fibrinous pleuritis, among other diseases, are discussed.

© 2011 The Authors. Respirology © 2011 Asian Pacific Society of Respirology.

In plain English

This was an invited narrative review by two US pathologists explaining pleural diseases to lung specialists. It reported no new research on patients. The authors reviewed pleural effusions, cancers spreading to the pleura, diffuse malignant mesothelioma, rarer pleural tumours, and non-cancerous pleural inflammation and scarring. Drawing on earlier work, they stated three things about asbestos and mesothelioma. About 80% of pleural diffuse malignant mesotheliomas in men are caused by asbestos exposure, with a lower percentage in women. The amphiboles amosite and crocidolite are established causes, while the role of other asbestos fibres is controversial. The time from first exposure to diagnosis can be 30 years or more. They described the disease as lethal, with most patients dead within a year of diagnosis. They wrote that occupational asbestos exposure had not been found to be a definitive cause of well-differentiated papillary mesothelioma, nor shown to cause solitary fibrous tumour. They also wrote that rounded atelectasis is often associated with asbestos exposure, and that pleural plaques may or may not be associated with occupational asbestos exposure. They stressed that accurate diagnosis is critical and can be very difficult on small biopsies.

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 (invited review in a series on pleural disease)
• Who was studied: No patients were studied. The authors reviewed published knowledge on primary and metastatic pleural tumours and non-cancerous pleural diseases, written for pulmonologists by two pathologists in New York and Texas, USA.
• Exposure: Asbestos was discussed as the main cause of diffuse malignant mesothelioma. The review named the amphiboles amosite and crocidolite as established causes and called the role of other asbestos fibres controversial. It also mentioned environmental exposures and chest radiation therapy as other causes.
• Main results:
  • The review stated that approximately 80% of pleural diffuse malignant mesotheliomas in men are caused by asbestos exposure, and that the percentage is lower for women.
  • The review stated that the role of asbestos fibres other than amosite and crocidolite in causing diffuse malignant mesothelioma is controversial.
  • The review stated that the latency period from first asbestos exposure to diagnosis of diffuse malignant mesothelioma can be 30 years or more.
  • The review described diffuse malignant mesothelioma as lethal and treatment-resistant. Most patients die within a year of diagnosis, and essentially all die within 2 years.
  • The review cited figures for the USA of about 200 000 pleural effusions each year from cancers spreading to the pleura, compared with about 1500 each year from diffuse malignant mesothelioma. That is a ratio of over 130 to 1.
  • The authors wrote that on pleural fluid cytology, immunostains cannot distinguish reactive mesothelial cell hyperplasia from diffuse malignant mesothelioma, so a biopsy or excision is required.
  • The review listed unequivocal invasion of mesothelial cells into the underlying lung or chest wall as the most reliable feature for diagnosing diffuse malignant mesothelioma.
  • The review stated that occupational asbestos exposure has not been found to be a definitive cause of well-differentiated papillary mesothelioma.
  • The review stated that occupational asbestos exposure has not been shown to be a cause of solitary fibrous tumour.
  • The review stated that rounded atelectasis ('folded lung') is often associated with asbestos exposure.
  • The review stated that pleural plaques may or may not be associated with occupational asbestos exposure, and that chronic fibrous pleuritis of various causes may also cause pleural plaques.
• The authors' conclusion: The authors concluded that, because pleural diseases look alike but differ greatly in treatment and outcome, accurate diagnosis is critical. They added that histological examination of pleural biopsies is extremely important for getting it right.
• Limitations the authors state:
  • The authors stated that a detailed discussion of the other rare primary pleural tumours was beyond the scope of the review.

Topics

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

Medical terms in this study, explained in our Lexicon: Pathology, Pleura, Neoplasm, Mesothelioma, Eosinophilic.

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