Non-clinical sciences/Pathology · Diagnostics

Special histology stains

What it means

Beyond H&E: Ziehl–Neelsen acid-fast bacilli (TB); Congo red amyloid (apple-green birefringence under polarised light); PAS glycogen/fungi/basement membranes; Perls' Prussian blue iron; Warthin–Starry silver spirochaetes/H. pylori; Grocott/GMS fungi.

Worked example

Apple-green birefringence of Congo-red-stained tissue under polarised light confirms amyloid.

In the exam

A renal biopsy stained with a particular dye shows apple-green birefringence under polarised light.

What settles it

Congo red = amyloid (apple-green birefringence); Ziehl–Neelsen = acid-fast bacilli. (Tested via the stain match set.)

Classically confused with

Tumour markers

Source: StatPearls — Histochemical stains