Special Stains and Molecular Analysis in Histopathology

A collection of flashcards covering key concepts, procedures, and applications of special stains and molecular analysis in histopathology.

What is the main purpose of light microscopy?

To magnify images and visualise differences in colour and brightness.

What is fluorescence microscopy used for?

To achieve precise localisation of molecules identified by antibodies.

What does superresolution microscopy provide?

Tools to circumvent physical limitations of light microscopy.

How does electron microscopy compare to light microscopy?

It provides a massive increase in resolution and illustrates ultrastructures.

What are the steps in tissue preparation for histochemistry?

Fixation, embedding, sectioning, and drying.

Why is H&E staining important?

It describes cell structures and highlights abnormalities for diagnosis.

What do special stains identify?

Specific structures or molecules in tissues.

What are considered 'special stains' in pathology?

Any histochemical staining other than H&E stain.

What is the significance of positive controls in special staining?

They ensure that a negative result does not indicate a negative diagnostic finding.

What does Alcian blue stain highlight?

Acid glycoproteins in structures like colonic crypts.

What structures does periodic acid Schiff (PAS) staining reveal?

Neutral glycoproteins, particularly in the liver.

How does differential staining enhance contrast?

By treating stained tissues with mordants or other solutions to increase visibility.

What do trichrome stains identify?

Cellular structures and connective tissue components.

In which condition can metaplasia occur?

When differentiated cell types transform into one another under acidic conditions.

What abnormalities can be seen with α1-antitrypsin deficiency?

Characteristic mucin granules identified by DPAS staining.

What does PAS staining help identify in infections?

Glycogen present in the cell walls of fungi.

What is the characteristic appearance of amyloid deposits?

Birefringent substances producing green and yellow/red colors.

What is the role of the Human Protein Atlas?

To map all human proteins across cells, tissues, and organs.

What is the importance of liquid biopsy?

It enables the analysis of circulating tumor cells and free tumor DNA from blood.

What technique is used to assess the expression of ERBB2 in tumors?

FISH analysis.

What are oncogenes?

Genes that can transform a cell into a tumor cell when activated.

What is a significant gene mutation analyzed before therapy decisions in lung cancer?

EGFR mutations.

How does pyrosequencing work?

It measures light produced as nucleotides are incorporated during DNA synthesis.

What are the advantages of next-generation sequencing (NGS)?

Massively parallel processing and high read depth.

What is the purpose of chromosomal painting?

To visualize specific chromosomes using sets of DNA probes.

What can RNA in situ hybridisation help analyze?

mRNA expression patterns in various cell types.

What significant gene mutation is analyzed in breast cancer?

Amplification of the HER2 gene (ERBB2).

What changes are observed in tissues with gastrointestinal cancers?

Adenocarcinomas can show stratified epithelium and glandular secretory mucosa.

Which stain is involved in identifying lipids?

Oil Red O staining.

What does Masson trichrome staining identify?

Collagen and other connective tissue components.

What is a key characteristic of Congo red staining?

Identification of amyloid deposits.

What is involved in analysis using RNA hybridisation?

Detecting specific miRNAs indicative of certain cancers.

What diagnostic challenge is presented by tissue fixation?

It can destroy structures of nucleic acids and proteins.

How do oncogenes influence cancer development?

Through mutations that lead to uncontrolled cell growth.

Why are certain stains more commonly used in research labs?

Due to their speed, ease of use, and cost-effectiveness.

What information does a chromosomal translocation indicate?

Reciprocal exchanges of segments between chromosomes.

What is the role of haptens in hybridisation techniques?

To label nucleic acid probes for detection with antibodies.

What do the colors produced in chromosome painting represent?

Different chromosomes labelled with specific fluorescent dyes.

How does hybridisation target DNA?

By denaturing the target DNA, often using heat or chemicals.

What are the components of the Human Protein Atlas's Tissue resource?

It shows the distribution of proteins across all major tissues and organs.

What structural components can be diagnosed in liver cirrhosis?

Fibrotic tissues and nodular changes.

What method is used to evaluate gene expression in tumours?

Integration of multi-omics data including RNA-seq and DNA analysis.

What is a limitation of conventional Sanger sequencing?

It has low sensitivity (~20%).