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Immunohistochemistry Flashcards

6 cards from real ASCP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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

    Answer: Eliminates endogenous biotin interference and provides consistent amplification

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

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

    Answer: Adenocarcinoma or urothelial carcinoma origin

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

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

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

    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.

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

    Answer: Synaptophysin or chromogranin

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

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

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

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

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

    Answer: The antibody binds to unintended antigens structurally similar to the target

    Cross-reactivity occurs when an antibody binds antigens other than its intended target due to shared epitopes, leading to false-positive staining.