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

Polymer systems eliminate false positives from endogenous biotin (a problem in liver, kidney, and adipose tissue) while providing high sensitivity without biotin-streptavidin interference.

Question 2

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

Accepted Answer

Adenocarcinoma or urothelial carcinoma origin

Answer

CK7 (cytokeratin 7) positivity indicates glandular epithelial origin, and combined with other markers, helps narrow the primary site of adenocarcinomas.

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

A failed positive control means the staining protocol did not work; any negative results from that run are technically invalid and the assay must be repeated.

Question 4

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

Accepted Answer

Synaptophysin or chromogranin

Answer

Synaptophysin and chromogranin A are neuroendocrine markers expressed in dense-core secretory granules of neuroendocrine cells and their neoplasms.

Question 5

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

Accepted Answer

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

Answer

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

ASCP - Histotechnician Test Practice Test

ASCP - Histotechnician Test Practice Test

ASCP Immunohistochemistry 3