ASCP Immunohistochemistry 2

Question 1

What does a negative IHC result on a poorly fixed specimen most likely represent?

Accepted Answer

False negative due to antigen destruction by inadequate fixation

Answer

True absence of the antigen

Answer

Successful antibody staining with no target present

Answer

Over-retrieval artifact

Question 2

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

Accepted Answer

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

Answer

To fix the tissue before antibody application

Answer

To enhance primary antibody penetration

Answer

To amplify signal detection

Question 3

Ki-67 IHC is used to assess what cellular property?

Accepted Answer

Cellular proliferation index

Answer

Apoptosis rate

Answer

Hormone receptor status

Answer

Lymphoid lineage

Question 4

What is the difference between the direct and indirect IHC methods?

Accepted Answer

Direct uses enzyme-labeled primary antibody; indirect uses unlabeled primary and enzyme-labeled secondary antibody

Answer

Direct uses two antibodies; indirect uses one

Answer

Direct is more sensitive than indirect

Answer

There is no practical difference

Question 5

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

Accepted Answer

Desmin or smooth muscle actin (SMA)

Answer

CK7

Answer

CD20

Answer

TTF-1

Question 6

Over-retrieval in heat-induced antigen retrieval (HIER) can cause which artifact?

Accepted Answer

Section detachment from the slide

Answer

Absence of all staining

Answer

Increased specific staining only

Answer

Blue background staining