[Histonet] Re: Congo Red Stain

[Bob Richmond]

If you're new to the congo red stain for amyloid:

You must have a positive control. Most of the controls I've seen
recently have been medullary carcinomas of the thyroid, which usually
(though not always) contain stainable amyloid.

I've asked many times on Histonet and never got a reply: amyloidosis
is fairly easily produced in experimental animals. Why isn't this
material used by pathologists as an amyloid control?

Supposedly paraffin sections of control tissue must be cut within a
month of use - the undeparaffinized sections deteriorate, though the
paraffin block themselves do not.

You must examine controls and patient sections using polarization. If
you don't have a polarizer on your microscope - and most pathologists
don't - then don't do the stain. The standard "jiss" - jiss use a pair
of broken sunglasses - is not satisfactory.

Anatech offers a stain they call "Amyloid Red" (it's clearly
characterized in their promotional material) - has anyone used it?

Bob Richmond
Samurai Pathologist
Maryville TN