[Histonet] Asbestos fibres in tissues

[Paul Bradbury]

Hi Fred,

I know you gave already had several replies to your question, but I 
would like to add my 2 cents worth.

Several years ago while I was still working in England, I was part of a 
major asbestososis-mesothelioma project. I was involved in examining 
tissues from several hundred autopsies for asbestos fibres and/or 
absbestos bodies. This project was initially sparked by the discovery of 
asbestos-associated diseases in elderly females none of whom had ever 
been employed in the industries traditionally associated with asbestos. 
To cut a long story short, these women, who were mainly housewives,  had 
been exposed to powdered asbestos while assembling gas-masks during 
World War II. The masks were intended to be used in the event of 
"poisonous gas" attacks (which never occurred). The exposure to asbestos 
was quite brief, sometimes only a couple of weeks working on the 
assembly line. But, some 25-30 years later, they presented with 
classical asbestos-associated diseases.

We did find patients with large numbers of asbestos fibres, but no 
asbestos bodies; patients with few fibres/bodies, but massive 
fibrosis/mesothelioma; and patients with large numbers of asbestos 
bodies, but little evidence of fibrosis, etc. We also found that 
specific types of asbestos were more likely to cause mesothelioma than 
other types.  Asbestos is a silicate and consequently will polarize 
light, however, the fibres can be very fine and easily overlooked by the 
inexperienced. After period of time, the ends of the fibres are coated 
by an iron-containing protein material, producing the classical 
"dumbell" shape. Additional protein-iron material will produce a fully 
coated fibre. Coated fibres are no longer birefringent when viewed by 
polarized light. The pathologist in charge of the project, Stephen 
Phillips Jones, wrote several articles on these topics, and went on the 
become on of Europe's most respected asbestosis experts.

As part of the project, we used a variety of procedures to find the most 
effective/efficient means of identifying the presence of asbestos fibres 
or bodies. The procedures we finally settled on require both fresh and 
fixed autopsy tissues. The procedure we used for fresh tissues is as 
follows:

Slice through a large portion of lung tissue (we routinely used the left 
lower lobe) to expose the parenchyma. Squeeze the tissues very firmly to 
extract the tissue fluids, using a funnel to collect the "juices" into a 
large plastic centrifuge tube is most convenient. This is a messy, 
bloody, seemingly crude procedure, but it works very well. Add a lysing 
reagent to the "juices" to get rid of the red cells, I believe we used 
saponin, but any lysing agent will work. Centrifuge the tissue fluid, 
discard most of the supernatent and make wet preparations from the 
concentrate. No staining is required. Asbestos bodies, if present, are 
very conspicuous and easily identified. Asbestos fibres, much finer and 
easily overlooked, can be identified by the use of polarized light.
The wet preps are not permanent and can be discarded after examination. 
The lung tissue must be unfixed. Autolysis and putrefaction do not have 
any effect on the asbestos content, although they make the procedure 
less pleasant.

For fixed tissues, we used the following  procedure. From each processed 
block of lung tissue, we cut a 30 micron section. This was dried as 
usual, dewaxed, coverslipped, and examined using brightfield and 
polarized light microscopy. Asbestos fibres or bodies were easily 
identified.The section does not require staining.

As other Histonet members have commented, asbestos bodies are strongly 
Perls' Prussian blue positive due to the ferric iron present in the 
coating. However, the morphology of the asbestos body is unmistakable 
and does not really require confirmation by special stains.

Some texts have recommended using microincineration to "cremate" the 
cellular tissue components and leave a residue of asbestos-containing 
ash that can be examined. We tried this method, but found it to be 
unreliable, time-consuming and generally a pain in the %$#.

Hope these thoughts help, if you need any more suggestions, let me know.

Sorry for the late response, but I was down in Florida for the past 
three weeks enjoying the beautiful weather, beaches, and scenery of the 
Gulf coast.

Paul Bradbury
Kamloops, BC, Canada










Fred Underwood wrote:

>Hi All,
>   
>     I asked this question earlier, but am not sure it got posted.  I'm
>looking for a technic to demonstrate asbestos fibers.  Possbily by
>digesting the tissue.  Thanks in advance.
>
>Fred Underwood HT(ASCP)
>Montgomery County Coroner
>Dayton,OH
>
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