Radiological diagnosis of crocidolite induced pleural mesotheliomata in the rat

Our plain-English summary of Radiological diagnosis of crocidolite induced pleural mesotheliomata in the rat, by M.S. McLachlan, J.C. Wagner (British Journal of Experimental Pathology, 1974).

The study

• Authors: M.S. McLachlan, J.C. Wagner
• Journal: British Journal of Experimental Pathology
• Published: 1974;55(2):164-8
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Free full text

Abstract

Crocidolite asbestos dust was inoculated intrapleurally in 36 rats. Chest radiographs were obtained up to 120 weeks after inoculation. Radiological and pathological observations were compared. In 3 animals, in which mesotheliomata were suspected radiologically, no evidence of malignancy was observed on histological examination. A radiological diagnosis suggesting probable or definite malignancy was made in all 7 animals with histologically proven mesotheliomata.

In plain English

This was an animal experiment testing whether chest X-rays of living rats could show which animals had developed pleural mesotheliomata, cancers of the lining around the lungs. The authors injected 20 mg of UICC crocidolite asbestos into the right pleural cavity of rats. They studied 36 of them, 18 of each sex, chosen at random from 88 injected animals and killed between 18 and 120 weeks after injection. X-rays taken in life were judged without knowledge of the pathology findings. All 36 rats developed pleural lesions, and 7 had mesotheliomata, the first seen 84 weeks after injection. All 7 were rated probably or definitely malignant on X-ray. Of 11 rats rated that way, 7 had mesotheliomata and 1 had changes suspicious of malignancy. Three of the 26 rats with benign lesions were wrongly suspected, which the authors called a false positive rate of 12%. Pleural calcification did not separate benign from malignant lesions. The authors concluded that agreement between X-ray and pathology findings was good.

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: Animal experiment: chest radiographs of living rats, assessed without knowledge of the pathological findings, compared with macroscopic (necropsy) and histological assessments
• Who was studied: 36 specific pathogen free Wistar/Alderley Edge ICI strain rats, 18 of each sex, taken at random from 88 rats inoculated with crocidolite and killed between 18 and 120 weeks after injection
• Exposure: 20 mg of UICC crocidolite in saline suspension injected into the right pleural cavity, 6 to 13 weeks (mean 9 weeks) after birth
• Main results:
  • All 36 rats in the study developed pleural lesions
  • Mesotheliomata were found in 7 of the 36 rats, the first 84 weeks after injection
  • None of the 7 histologically proven mesotheliomata was missed on X-ray; all were rated probably or definitely malignant
  • Of 11 rats rated probably or definitely malignant on X-ray, histology confirmed mesotheliomata in 7 and showed changes suspicious of malignancy in 1 more
  • Mesotheliomata were wrongly suspected on X-ray in 3 of the 26 rats with histologically benign lesions, a false positive rate of 12%
  • Macroscopic (naked-eye) examination at necropsy correctly identified 5 of the 7 histologically confirmed mesotheliomata
  • X-ray diagnosis of histologically proven malignancy was more accurate than macroscopic assessment
  • Tumours large enough to push the mediastinum aside, or showing spread to the other side of the chest on X-ray, were always histologically malignant
  • Pleural fluid was always found at necropsy when mesotheliomata were present, but was never recognized with certainty on X-ray
  • Pleural calcification did not distinguish benign from malignant lesions
• The authors' conclusion: The authors concluded that agreement between their pathological observations and X-ray examination in life was good
• Limitations the authors state:
  • The X-ray diagnosis of mesothelioma was generally based on how extensive the disease was rather than on specific features
  • Post-mortem X-rays were often unhelpful and potentially misleading, because lung deflation after death obscured disease

Topics

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

Medical terms in this study, explained in our Lexicon: Crocidolite, Chest X-Ray.

Related studies

• Pluripotential nature of mesotheliomata induced by inhalation of erionite in rats — N.F. Johnson, R.E. Edwards, et al. (1984)
• Mesotheliomata in rats after inoculation with asbestos and other materials — J.C. Wagner, G. Berry, et al. (1973)
• Clinical and radiological criteria for the differential diagnosis between asbestosis and idiopathic pulmonary fibrosis: Application in two cases — A. Stufano, A. Scardapane, et al. (2021)
• Bronchiolar and alveolar lesions in the pathogenesis of crocidolite-induced pulmonary fibrosis in mice — D.H. Bowden, I.Y. Adamson (1985)
• Apoptosis induced by crocidolite asbestos in human lung epithelial cells involves inactivation of Akt and MAPK pathways — A. Baldys, P. Pande, et al. (2007)
• Asbestotic radiological abnormalities among United States merchant marine seamen — I.J. Selikoff, R. Lilis, et al. (1990)

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