Mixed Deck — All ASCP Topics Flashcards

What staining result indicates that sections were not completely deparaffinized before H&E staining?

Answer: Unstained or poorly stained areas with paraffin residue

Residual paraffin acts as a barrier to aqueous dyes, producing unstained patches or areas with poor dye penetration.

What is the primary purpose of fixation in tissue processing?

Answer: To prevent autolysis and preserve tissue morphology

Fixation prevents autolysis and microbial decomposition by cross-linking proteins to preserve tissue architecture.

What is the purpose of the water bath used during paraffin sectioning?

Answer: To float and flatten sections by removing compression wrinkles

The water bath (typically 40–45°C) allows compressed sections to expand and flatten before being picked up on slides.

What IHC marker is used to confirm the presence of muscle differentiation in a tumor?

Answer: Desmin or smooth muscle actin (SMA)

Desmin and smooth muscle actin are cytoskeletal proteins expressed in muscle cells; their IHC positivity confirms muscle differentiation in tumor cells.

What does a reagent QC failure on a negative control indicate?

Answer: Non-specific or background staining is present, suggesting a reagent or protocol problem

A positive signal on a negative control means non-specific staining is occurring, which could lead to false-positive results in patient samples.

What is the term for the process of surrounding embedded tissue with paraffin wax in a mold?

Answer: Embedding

Embedding is the process of orienting tissue in molten paraffin within a mold to create a block for sectioning.

In a well-stained H&E section, red blood cells (RBCs) should appear what color?

Answer: Bright red/orange

RBCs lack nuclei and stain brightly eosinophilic (bright red to orange) due to their hemoglobin content.

What is the purpose of the dehydration step in tissue processing?

Answer: To remove water before infiltration with paraffin

Dehydration removes water from tissue using ascending grades of alcohol so the tissue can be infiltrated with paraffin wax.

Which stain is most commonly used for rapid intraoperative frozen section evaluation?

Answer: Hematoxylin and eosin (H&E)

H&E is the standard rapid stain for frozen sections because it provides quick nuclear and cytoplasmic contrast for diagnostic evaluation.

What is the ideal pH range for neutral buffered formalin to prevent artifact formation?

Answer: 6.8–7.4

NBF should be maintained between pH 6.8 and 7.4 to prevent the formation of formalin pigment (acid formaldehyde hematin) and optimize tissue preservation.

What is the minimum required documentation for each H&E staining run in an accredited laboratory?

Answer: Reagent lot numbers, dates, technician ID, and control results

Accreditation standards require each staining run to be documented with reagent lot numbers, preparation/expiration dates, technician identification, and control staining results.

What is the purpose of sectioning a 'waste' ribbon before collecting diagnostic sections?

Answer: To remove surface paraffin and expose full tissue depth

Cutting and discarding initial waste sections removes the trimmed surface layer and reveals intact tissue at the proper depth.

Which personal protective equipment (PPE) is required when handling formalin-fixed specimens in the histology laboratory?

Answer: Gloves, lab coat, and eye protection at minimum

Formalin is a known carcinogen and respiratory irritant; minimum PPE includes nitrile gloves, lab coat, and eye protection when handling formalin-fixed specimens.

Before H&E staining, paraffin sections must be deparaffinized using which reagent?

Answer: Xylene

Xylene dissolves paraffin wax before the section is rehydrated through graded alcohols for aqueous staining.

In IHC, what is the function of the blocking step with normal serum?

Answer: To prevent non-specific binding of the secondary antibody to tissue proteins

Normal serum (from the species used to raise the secondary antibody) saturates non-specific protein binding sites, reducing background staining.

What is the purpose of the mordant in the hematoxylin staining process?

Answer: To link the hematoxylin dye to tissue components

A mordant (typically alum) acts as a bridge between the dye and tissue, forming a stable dye-mordant-tissue complex.

Melanoma cells are typically IHC positive for which set of markers?

Answer: S100, HMB-45, Melan-A (MART-1)

S100, HMB-45, and Melan-A are melanocytic differentiation markers used in combination to confirm melanoma diagnosis.

What processing artifact results from inadequate fixation before processing?

Answer: Autolysis

Inadequate fixation allows continued enzymatic activity, leading to autolysis and degraded tissue morphology.

What is the purpose of the differentiation step using acid-alcohol in H&E staining?

Answer: To selectively remove excess hematoxylin from non-nuclear elements

Acid-alcohol removes excess hematoxylin from cytoplasm and connective tissue, leaving stain only in the nuclei.

Under CLIA regulations, who is responsible for the overall operation and administration of a histology laboratory?

Answer: The laboratory director

CLIA designates the laboratory director as ultimately responsible for all laboratory operations, test performance, quality, and regulatory compliance.