HTL Immunohistochemistry & Special Stains 5

Question 1

Which special stain is used to demonstrate reticulin fibers in tissue, particularly in liver and bone marrow biopsies?

Accepted Answer

Gordon and Sweet's silver impregnation (reticulin stain)

Answer

Gordon and Sweet's silver impregnation stains reticulin (type III collagen) fibers black, essential for evaluating fibrosis in liver and marrow.

Question 2

Tyramide signal amplification (TSA) in IHC is used primarily when:

Accepted Answer

The antigen is scarce or antibody affinity is low, requiring enhanced sensitivity

Answer

TSA deposits large amounts of tyramide-hapten at HRP sites, dramatically amplifying signal for low-abundance antigens.

Question 3

Which IHC marker is positive in both Schwann cells and melanoma, making it useful but non-specific in differential diagnosis?

Accepted Answer

S100 protein

Answer

S100 is expressed in Schwann cells, melanocytes, Langerhans cells, and many other cell types, limiting its specificity despite high sensitivity for melanoma.

Question 4

The Oil Red O stain must be performed on which type of tissue section, and why?

Accepted Answer

Frozen sections, because lipids are dissolved by paraffin processing solvents

Answer

Lipids are dissolved by the alcohols and xylene used in routine paraffin processing, so Oil Red O must be performed on frozen sections.

Question 5

In multiplex IHC/IF, which approach allows simultaneous detection of multiple antigens on the same tissue section?

Accepted Answer

Applying all primary antibodies from different species with species-specific secondaries or using tyramide cycling

Answer

Multiplex IHC uses species-specific secondaries for different primaries, or cyclic tyramide-based platforms to sequentially deposit distinguishable reporters for multiple antigens.

(HTL) Histotechnology Certification Practice Test

(HTL) Histotechnology Certification Practice Test

HTL Immunohistochemistry & Special Stains 5