HTL Immunohistochemistry & Special Stains 4

Question 1

The Ziehl-Neelsen (acid-fast) stain differentiates mycobacteria because their cell walls contain which substance that retains carbol fuchsin?

Accepted Answer

Mycolic acid

Answer

Mycobacterial cell walls contain mycolic acid, a waxy lipid that resists decolorization with acid-alcohol after carbol fuchsin staining.

Question 2

In a positive IHC control tissue, staining is absent but the negative control (no primary antibody) is also negative. What does this indicate?

Accepted Answer

Primary antibody failure or antigen loss in control tissue

Answer

When the positive control fails but the negative control is clean, the primary antibody has likely failed or the antigen was lost, invalidating the run.

Question 3

Which IHC marker is used to identify plasma cells in tissue sections?

Accepted Answer

CD138 (syndecan-1)

Answer

CD138 (syndecan-1) is a plasma cell marker used to identify plasma cell differentiation and myeloma in tissue sections.

Question 4

The mucicarmine stain is particularly useful for demonstrating which organism in tissue due to its thick capsule?

Accepted Answer

Cryptococcus neoformans

Answer

Mucicarmine stains the thick polysaccharide capsule of Cryptococcus neoformans deep rose-red, aiding identification.

Question 5

Which IHC marker combination is used to confirm the diagnosis of hepatocellular carcinoma (HCC) versus metastatic adenocarcinoma?

Accepted Answer

HepPar-1+, arginase-1+, glypican-3+

Answer

HepPar-1, arginase-1, and glypican-3 are hepatocellular markers that support HCC diagnosis over metastatic adenocarcinoma.

(HTL) Histotechnology Certification Practice Test

(HTL) Histotechnology Certification Practice Test

HTL Immunohistochemistry & Special Stains 4