ASCP Immunohistochemistry 3

Question 1

What is the purpose of using the polymer-based detection system (e.g., EnVision) over ABC in IHC?

Accepted Answer

Eliminates endogenous biotin interference and provides consistent amplification

Answer

Lower cost

Answer

Requires fewer wash steps

Answer

Uses a different chromogen

Question 2

What does diffuse cytoplasmic staining for CK7 suggest in a carcinoma workup?

Accepted Answer

Adenocarcinoma or urothelial carcinoma origin

Answer

Squamous cell carcinoma

Answer

Neuroendocrine differentiation

Answer

Melanoma

Question 3

What is the significance of a negative IHC result when the positive control is also negative?

Accepted Answer

The staining run failed — results are invalid and the test must be repeated

Answer

The tumor is truly antigen-negative

Answer

The antibody worked but the tumor lacked the antigen

Answer

Background inhibited staining

Question 4

Which IHC marker is used to identify neural/neuroendocrine differentiation in tumors?

Accepted Answer

Synaptophysin or chromogranin

Answer

CD3

Answer

MNF116

Answer

CK20

Question 5

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

Accepted Answer

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

Answer

CD45, CD20, CD3

Answer

CK7, CK20, CEA

Answer

SMA, desmin, CD34

Question 6

What does the term 'cross-reactivity' mean in the context of IHC antibody specificity?

Accepted Answer

The antibody binds to unintended antigens structurally similar to the target

Answer

The antibody stains both frozen and paraffin sections

Answer

The antibody works with multiple chromogens

Answer

The primary antibody reacts with the secondary antibody