The extrapleural space

Our plain-English summary of The extrapleural space, by B. Felson (Seminars in Roentgenology, 1977).

The study

• Author: B. Felson
• Journal: Seminars in Roentgenology
• Published: 1977;12(4):327-33
• Cited by: 11 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Summary of the article

This review by a radiologist described the extrapleural space, a potential plane in the loose connective tissue of the endothoracic fascia between the parietal pleura and the thoracic cage, and how lesions there appear on chest radiographs. The article was originally published in the book Chest Roentgenology (1973) and was illustrated with radiographs of individual cases. The author described what he called the extrapleural sign: a very sharp convex outline facing the lung with tapering upper and lower margins. It was often accompanied by rib involvement and by movement with the ribs rather than the lung on breathing. He compared this appearance with encapsulated and interlobar pleural fluid, pulmonary tumors, localized pleural tumors and malignant mesothelioma. He noted that mesothelioma usually shows a smaller transverse diameter, pleural thickening elsewhere and often effusion, though it may rarely arise entirely extrapleurally. He recommended fluoroscopy with spot films to bring lesions into profile, and Bucky films to show rib changes. By far the commonest cause of the sign was metastatic tumor in a rib. Other causes included myeloma, lymphoma, primary neoplasms, lipoma, infections, hematoma, oil plombage for tuberculosis, operations, and congenital lobar agenesis. He also described lesions spreading between the lung, pleura and chest wall, notably in actinomycosis.

PubMed has no abstract for this study, and the article doesn't print one. We wrote this summary from the full article with the help of AI. It is not the authors' wording.

In plain English

This is a radiology teaching article by a single author, not a study of patients or of asbestos. It is a reprint of a chapter first published in the 1973 book Chest Roentgenology. It does not mention asbestos. It described how lesions in the extrapleural space, the layer between the parietal pleura and the rib cage, look on chest X-rays. The author named a pencil-sharp convex outline with tapering margins the 'extrapleural sign', and wrote that the sign cannot be considered pathognomonic (decisive on its own) of disease in this location unless rib involvement is shown. By far the commonest cause was metastatic tumor in a rib. The author wrote that malignant mesothelioma of the pleura can look similar on X-ray. It usually shows a smaller transverse diameter, thickening in other pleural areas, and often pleural effusion. Rarely, a mesothelioma may arise from the outer surface of the parietal pleura and be entirely extrapleural. The article gave no counts, rates or statistics. It was illustrated with X-rays of individual patients.

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 and teaching article on chest X-ray appearances, illustrated with individual patient X-rays. It is a reprint of a 1973 textbook chapter.
• Who was studied: No defined study population. The article was illustrated with chest X-rays of individual patients, for example a 16-year-old boy with a fibrous mesothelioma in the right major fissure. No numbers of patients are given.
• Exposure: Not applicable. The article does not discuss asbestos or any other exposure.
• Main results:
  • A lesion in the extrapleural space shows an extremely sharp convex outline facing the lung.
  • The author defined the 'extrapleural sign' as a pencil-sharp convex outline with tapering margins.
  • These changes cannot be considered pathognomonic of extrapleural disease unless rib involvement is demonstrated.
  • According to the author, the commonest cause of the sign is metastatic tumor in a rib.
  • A localized primary tumor of the pleura can give X-ray signs identical to an extrapleural lesion, except for the tapering margins.
  • Compared with an extrapleural lesion, malignant mesothelioma shows a smaller transverse diameter, thickening in other pleural areas, and often pleural effusion.
  • Rarely, a mesothelioma may arise from the external surface of the parietal pleura and be entirely extrapleural.
  • Encapsulated pleural effusion, especially when longstanding, may produce similar X-ray findings.

Topics

Medical terms in this study, explained in our Lexicon: Endothoracic Fascia, Parietal Pleura, Chest X-Ray, Malignant Mesothelioma, Mesothelioma, Pleural Thickening, Myeloma, Neoplasm.

Related studies

• Increased body mass index is related to apparent circumscribed pleural thickening on plain chest radiographs — Y.C. Lee, C.K. Runnion, et al. (2001)
• Managing the pneumonectomy space after extrapleural pneumonectomy: postoperative intrathoracic pressure monitoring — A.S. Wolf, F.L. Jacobson, et al. (2010)
• Extrapleural and cardiophrenic lymph nodes: prevalence, clinical significance and diagnostic value — B. Feragalli, C. Mantini, et al. (2014)
• Aetiology of pleural plaques — V. Rous, J. Studený (1970)
• Length-dependent retention of carbon nanotubes in the pleural space of mice initiates sustained inflammation and progressive fibrosis on the parietal pleura — F.A. Murphy, C.A. Poland, et al. (2011)
• Exposure to asbestos and mesothelioma of the pleura — P.B. Fowler, J.C. Sloper, et al. (1964)

Browse more research in Seminars in Roentgenology, or return to medical research.