[Histonet] Re: best controls

[Bob Richmond]

What controls for trichrome, methenamine silver fungal stain, and hemosiderin?

For trichrome, whatever keeps the regulatory agencies happy.
Pathologists use it mostly for liver biopsies, so an autopsy liver
with early hepatic fibrosis would be ideal. But I don't bother to look
at the control.

GMS methenamine silver for fungi: I'd want histoplasma growing in
human tissue, with numerous yeast forms with a history of bad
staining. But you take what you can get. A Candida culture injected
into a mouse lung is what I expect to see.

Hemosiderin: any tissue with hemosiderin in it. Dog spleen or liver
works quite well - unlike people, dogs store a lot of iron. Human
hemochromatotic tissue is hard to get, and I'd hope increasingly
difficult.

Could I add amyloid? The only control I can usually get is human
medullary thyroid carcinoma. Amyloidosis is easily induced in
experimental animals, and I've asked on Histonet several times - why
isn't this tissue available for clinical use?

And acid-fast? Once again, I expect mouse lung injected with AFB. The
best I've ever seen was rhesus monkey lung, those pestiferous New
Delhi monkeys come to autopsy. Leprosy requires a separate AFB
control. Once again, why not animal material. Leprosy is easily
produced in armadillos (Dasypus novemcinctus), and one lepradillo
could supply the world for a century.

Bob Richmond
Samurai Pathologist
Knoxville TN