Practice Test Geeks(HTL) Histotechnology Certification Practice Test
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Immunohistochemistry & Special Stains Flashcards

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

    Answer: Mycolic acid

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

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

    Answer: Primary antibody failure or antigen loss in control tissue

    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.

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

    Answer: CD138 (syndecan-1)

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

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

    Answer: Cryptococcus neoformans

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

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

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

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

  6. The Perls' Prussian blue reaction detects iron in tissue by forming which compound?

    Answer: Ferric ferrocyanide (Prussian blue) precipitate

    Hydrochloric acid releases ferric ions from storage proteins; these react with potassium ferrocyanide to form insoluble Prussian blue precipitate.

  7. In IHC for hormone receptor status in breast carcinoma, what is the minimum percentage of positive nuclear staining that defines ER positivity per ASCO/CAP guidelines?

    Answer: 1%

    Per 2020 ASCO/CAP guidelines, ER is considered positive if ≥1% of tumor nuclei show staining, though very low positivity (1–10%) is reported separately.

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