The prevalence of enlarged mediastinal lymph nodes in asbestos-exposed individuals: a CT study

Our plain-English summary of The prevalence of enlarged mediastinal lymph nodes in asbestos-exposed individuals: a CT study, by C. Sampson, D.M. Hansell (Clinical Radiology, 1992).

The study

• Authors: C. Sampson, D.M. Hansell
• Journal: Clinical Radiology
• Published: 1992;45(5):340-2
• Cited by: 14 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Patients with cryptogenic fibrosing alveolitis have a higher prevalence of enlarged mediastinal lymph nodes compared with the normal population. To determine whether or not this observation applies to individuals with asbestos-induced pulmonary fibrosis the high resolution computed tomography (CT) scans of 14 patients with definite asbestosis and 11 age-matched cases with benign asbestos-induced pleural disease, but no lung disease, were re-imaged on soft tissue settings. The site, size and number of mediastinal lymph nodes equal to, or greater than, 1.2 cm were recorded. In the asbestosis group 14 out of 14 patients had at least one enlarged lymph node with an average number per individual of four (range 1-10). In the control group two out of 11 patients each had one minimally enlarged lymph node. We conclude that mediastinal lymph node enlargement occurs frequently in asbestosis: awareness of this is important in the investigation of malignant disease in patients with asbestosis.

In plain English

This London study asked whether people with asbestosis (lung scarring from asbestos) often have enlarged lymph nodes in the middle of the chest without cancer. The authors reviewed CT scans of 61 men assessed for asbestos-related lung disease over one year. They studied 14 with calcified pleural plaques and lung fibrosis, and an age-matched group of 11 with plaques but no fibrosis. None had chest cancer, or chest infection in the 3 months before scanning. Non-calcified nodes 1.2 cm or larger were counted. All 14 with asbestosis had at least one enlarged node, 1 to 10 each (mean 3.7). In the comparison group, 2 of 11 had one each. The difference was statistically significant (P less than 0.001). At clinical review 6 months to 1 year later, no cancer was found in the asbestosis group. The authors concluded that node enlargement is associated with asbestosis without cancer or infection and should not be assumed to mean cancer spread. They noted node size may have been underestimated and node numbers probably were, hilar nodes were not assessed, and tissue confirmation was not possible.

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: Review of existing CT scans comparing two groups of asbestos-exposed patients (asbestosis versus pleural plaques without lung fibrosis)
• Who was studied: From 61 male patients assessed for asbestos-related lung disease over one year at the Royal Brompton National Heart and Lung Hospital, London: 14 consecutive patients with asbestosis (ages 65 to 77, mean 70) and an age-matched control group of 11 consecutive patients with calcified pleural plaques but no interstitial fibrosis (ages 59 to 80, mean 67). Patients were included only if they had no chest infection (intrathoracic sepsis) for at least 3 months before scanning and no chest cancer.
• Exposure: Asbestos exposure, required to be clearly documented. Fiber types, jobs and doses were not reported. The groups differed by whether the patients had asbestosis (interstitial lung fibrosis on CT).
• Main results:
  • Method: the number, size and site of mediastinal lymph nodes 1.2 cm or larger were recorded. Calcified lymph nodes were not measured.
  • Asbestosis group: all 14 patients had at least one mediastinal lymph node 1.2 cm or larger.
  • Asbestosis group: the number of enlarged nodes per patient ranged from 1 to 10, with a mean of 3.7.
  • Asbestosis group: enlarged nodes occurred slightly more often in the pre-tracheal region.
  • Pleural plaque control group: 2 of 11 patients had enlarged nodes, one each, measuring 1.2 cm and 1.4 cm.
  • The association of enlarged nodes with asbestosis was statistically significant (P less than 0.001, chi-squared test).
  • No patient had a repeat CT scan. At clinical review 6 months to 1 year later, there was no evidence of cancer in the asbestosis group.
• The authors' conclusion: The authors concluded that enlarged mediastinal lymph nodes are associated with asbestosis in the absence of cancer or infection. In patients with asbestosis who develop cancer, enlarged nodes should therefore not be assumed to be due to metastatic disease.
• Limitations the authors state:
  • The scans used a high resolution protocol with gaps between thin sections, which may have caused node size to be underestimated.
  • Hilar lymph nodes were not assessed because no intravenous contrast was given.
  • The scans were not designed to detect enlarged nodes, so the authors considered it probable that the number of enlarged nodes was underestimated.
  • The findings could not be checked against tissue samples.

Topics

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

Medical terms in this study, explained in our Lexicon: Mediastinal Lymph Nodes, Pulmonary Fibrosis.

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