Characteristics of asbestos concentration in lung as compared to asbestos concentration in various levels of lymph nodes that collect drainage from the lung

Our plain-English summary of Characteristics of asbestos concentration in lung as compared to asbestos concentration in various levels of lymph nodes that collect drainage from the lung, by R.F. Dodson, S. Shepherd, J. Levin, et al (Ultrastructural Pathology, 2007).

The study

• Authors: R.F. Dodson, S. Shepherd, J. Levin, S.P. Hammar
• Journal: Ultrastructural Pathology
• Published: 2007;31(2):95-133
• Type of article: Case report
• Cited by: 19 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Inhaled dust particulates are able to relocate to the extrapulmonary compartments, particularly the lymph nodes that drain the lung. There is little information about the concentration and type of asbestos in the lymphatics and lymph nodes. Quantitative analysis of asbestos lymph node burden conducted by light and analytical transmission electron microscopy has shown ferruginous bodies in lymph nodes that drain the lung and appreciable numbers of short asbestos fibers accumulate in lymph nodes in occupationally exposed individuals. The location of lymph nodes in the thoracic cavity was categorized according to the Naruke anatomical map. Tissue from eleven individuals with a history of asbestos exposure were selected for a comparative study of the asbestos content of lung with that found in the thoracic lymph nodes. The study used a digestion technique for tissue preparation and evaluated ferruginous body burden and concentration of asbestos fibers (> 0.5 microm in length). Comparison was made between sites and analysis was made as to the population of fibers detectable by light microscopy and defined as "Stanton fibers." The findings indicated the vast majority of all asbestos fiber types in all sites were shorter than 5 microm and would not have been counted in a light microscopy count scheme that included only those fibers > 5 microm. There were reproducible patterns of asbestos types of found in various lymph nodes, although there were variations in the amount of asbestos found in the sites sampled. In summary, asbestos fibers found in thoracic lymph nodes have predominately short fibers and, in this study group, consisted of a mixture of commercial and noncommercial amphiboles. When a long/thin fiber was found in the lung or lymph tissue, its detection required the use of analytical transmission electron microscopy for identification.

In plain English

This study measured asbestos in lung tissue and in chest lymph nodes from 11 men reported to have had occupational asbestos exposure. They died of mesothelioma or lung cancer or, in one case, a sinus cancer. Lymph nodes were labelled by level using the Naruke map. Tissue was chemically digested and examined by light microscopy for ferruginous (coated) bodies, and by analytical transmission electron microscopy for uncoated fibers at least 0.5 micrometres long. By light microscopy, ferruginous bodies were found in lung from every case except case 7. Electron microscopy did find one lightly coated, chrysotile-cored body in that case's lung, and all of its sampled lymph node levels contained ferruginous bodies. Seven of the 11 cases had more ferruginous bodies per gram in at least one lymph node site than in lung. Amphiboles, particularly crocidolite and amosite, predominated except in case 7, where chrysotile made up most lung fibers. Lymph node fibers were on average shorter than lung fibers, and the overall geometric mean length was 3.5215 micrometres. The authors reported that few lymph node fibers would be detectable by light microscopy. They concluded that comparing lung with lymph node sites gives the most comprehensive data on fiber burden and past exposure.

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: Laboratory tissue fiber-burden study of 11 cases (case series) comparing lung tissue with thoracic lymph nodes, using light microscopy and analytical transmission electron microscopy (ATEM)
• Who was studied: 11 males reported to have had past occupational asbestos exposure, whose cause of death was lung cancer or mesothelioma or, in one case, a left paranasal sinus squamous cell carcinoma. The tissue was discarded material from referrals to one author's pathology laboratory and included right lung, left lung and lymph nodes defined by the Naruke map.
• Exposure: Reported past occupational asbestos exposure. Table 1 lists jobs including Navy and shipyard sheet metal work, merchant marine engine-room work, plumbing and pipefitting, work at a chrysotile mining company, and work at an asbestos cement (transite) pipe facility. In tissue, the study measured ferruginous bodies and uncoated chrysotile, amosite, crocidolite, tremolite, actinolite and anthophyllite fibers at least 0.5 micrometres long with a length-to-width ratio greater than 5:1.
• Main results:
  • By light microscopy, ferruginous bodies were found in at least one lung sample from every case except case 7.
  • In case 7, ATEM found one ferruginous body formed on a chrysotile core in the lung digest. It had very little coating, and none had been detected in that lung tissue by light microscopy.
  • In case 7, all lymph node levels sampled contained ferruginous bodies, although none were found in the lung tissue by light microscopy.
  • Seven of the 11 cases had more ferruginous bodies per gram of lymph node tissue, in 1 to 4 sites, than in their lung tissue.
  • The highest lymph node ferruginous body burden was in the level 7 node of case 8: 25,200 per gram of wet tissue.
  • By ATEM, 164 ferruginous bodies were identified in lung digestates. Of these, 101 had amosite cores and 57 had crocidolite cores.
  • By ATEM, 22 ferruginous bodies were found in lymph node digestates. Of these, 16 had amosite cores and 6 had crocidolite cores.
  • The highest uncoated fiber count in composite lung samples was in case 4: 2,052,566 fibers per gram of wet tissue. Case 8 was second with 1,004,532. In both, the majority fiber type was crocidolite.
  • In case 8, the right level 10 and 12 lymph nodes contained 61,473,251 asbestos fibers per gram of wet tissue.
  • Lymph nodes had more asbestos fibers per gram than lung tissue except for a few specific nodes in limited cases.
  • Outside case 7, lung and lymph node fiber burdens showed a preponderance of amphiboles, particularly amosite and crocidolite.
  • In case 7, the majority of uncoated lung fibers were chrysotile. Only cases 4, 5 and 7 had appreciable chrysotile concentrations in lung tissue.
  • Average fiber length was longer in lung than in lymph nodes. The authors reported all averages as below 5 micrometres, with an overall geometric mean length of 3.5215 micrometres.
  • The authors also counted 'Stanton' fibers, defined as longer than 8 micrometres and thinner than 0.25 micrometres. In lung (all cases), the fiber types with the highest share meeting this definition were crocidolite (24.6%), chrysotile (19.8%) and amosite (15.6%). In lymph nodes, the vast majority of fibers did not meet it.
  • The authors reported that essentially no chrysotile and few crocidolite fibers from lymph nodes would be detectable by light microscopy, because the fibers were shorter than 5 micrometres or too thin.
• The authors' conclusion: The authors concluded that comparing multiple lung sites with extrapulmonary (lymph node) sites, when available, gives the most comprehensive data on fiber burden and insight into past exposure.
• Limitations the authors state:
  • Because of node proximity or small amounts of tissue, tissue from some adjacent lymph node levels was combined in some cases.

Topics

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

Medical terms in this study, explained in our Lexicon: Analytical Transmission Electron Microscopy (ATEM), Ferruginous Bodies, Asbestos Exposure, Ferruginous body, Stanton Fibers, Amphibole Group.

Related studies

• Asbestos fibers in para-aortic and mesenteric lymph nodes — T. Uibu, E. Vanhala, et al. (2009)
• Pleural mesothelioma in a woman whose documented past exposure to asbestos was from smoking asbestos-containing filtered cigarettes: the comparative value of analytical transmission electron microscopic analysis of lung and lymph-node tissue — R.F. Dodson, S.P. Hammar (2006)
• A comparison of asbestos burden in lung parenchyma, lymph nodes, and plaques — R.F. Dodson, M.G. Williams, et al. (1991)
• Asbestos content of lung tissue, lymph nodes, and pleural plaques from former shipyard workers — R.F. Dodson, M.G. Williams, et al. (1990)
• Asbestos content in the lymph nodes of nonoccupationally exposed individuals — R.F. Dodson, J. Huang, et al. (2000)
• Elemental and immunohistochemical analysis of the lungs and hilar lymph node in a patient with asbestos exposure, a pilot study — Y. Koga, T. Satoh, et al. (2016)

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