For doctorsA working command of histochemical stains (PAS/D-PAS, GMS, ZN, reticulin, Masson trichrome, Congo red, Perls) accelerates diagnosis. Reproducibility depends on standardised timing and reagent quality, which automated staining supports.
For patientsSometimes the lab uses extra colour stains to look for specific things like infections or fibrosis, helping reach a precise diagnosis.
Why H&E is not always enough
H&E reveals architecture and cytology, but many questions need a targeted histochemical stain.
A quick reference
- PAS / D-PAS: fungi, basement membranes, glycogen (D-PAS distinguishes glycogen).
- GMS: fungi and Pneumocystis, with crisp contrast.
- Ziehl-Neelsen: acid-fast bacilli (tuberculosis, leprosy) — highly relevant in India.
- Reticulin: architecture in liver and marrow, nodularity.
- Masson trichrome: collagen/fibrosis.
- Congo red: amyloid (apple-green birefringence).
- Perls: iron.
Technique decides the result
Special stains are timing-sensitive and reagent-dependent; inconsistent technique produces weak or false results. Standardised, programmable staining with managed reagents delivers the reproducibility these stains demand — particularly important for high-volume TB workloads.
Key takeaways- Special stains answer questions H&E cannot.
- ZN for acid-fast bacilli is especially relevant in India.
- Results are timing- and reagent-sensitive.
- Programmable staining improves reproducibility.
Related equipment
Automated Slide Stainer · LSM-520
Unimeditrek Automated Slide Stainer LSM-520 — programmable linear staining system for H&E and special stains, delivering
Histopathology Consumables
Unimeditrek range of histopathology consumables — blades, cassettes, reagents and accessories for the complete histology
FAQs
Which stain for suspected fungal infection?
PAS and GMS are the workhorses; GMS gives high-contrast demonstration of fungal elements.
How is amyloid confirmed?
Congo red showing apple-green birefringence under polarised light.