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The QIHC exam has 50 questions and runs 1 hours 30 minutes.
These 10 free QIHC questions are organized by exam domain, so you can see how each part of the Qualification in Immunohistochemistry blueprint is tested. Reveal the answer and explanation under each question.
Renal tubules develop brown cytoplasmic staining with a streptavidin-HRP detection method. On a serial section, the same staining appears when both primary and secondary antibodies are omitted but streptavidin-HRP is retained. A section exposed only to DAB and hydrogen peroxide remains unstained. What accounts for this contrast?
Correct answer: A - Endogenous tissue biotin binding the streptavidin-HRP reagent
A heavily pigmented lesion is being stained with a validated HRP method that uses classical AEC to provide a red signal distinguishable from brown melanin. The red reaction is crisp when development ends. To preserve that distinction in the finished slide, select the compatible finishing sequence.
Correct answer: B - Rinse in water and apply an AEC-compatible aqueous mountant
A dermatologist plans separate biopsies for routine histology and direct immunofluorescence in a patient with a suspected autoimmune blistering disorder. The laboratory has supplied Michel's transport medium for the immunofluorescence specimen. Which sampling site offers the best opportunity to preserve diagnostically useful immunoreactants?
Correct answer: D - Intact perilesional skin adjacent to a fresh blister
A laboratory's heat-retrieval procedure specifies 20 minutes at 98°C. After a heating unit is replaced, several nuclear markers become weak despite unchanged buffer, antibodies, and detection reagents. The new unit's 20-minute cycle includes warm-up; an independent probe shows that the buffer stays at 98°C for only the final eight minutes. Morphology remains intact. Which adjustment addresses the demonstrated failure?
Correct answer: A - Restore the full holding time at the validated temperature
In a colorectal carcinoma, tumor nuclei lack MLH1 and PMS2 but retain MSH2 and MSH6. Lymphocytes and stromal cells stain appropriately for all four proteins on their respective slides. The tumor is viable, and no staining artifact is present. The preliminary interpretation should be:
Correct answer: C - Deficient mismatch-repair expression with loss of MLH1 and PMS2
An antibody titration gives the following results: 1:50 and 1:100 stain both the intended cells and known-negative epithelium; 1:200 retains the required weak-positive cells without staining the negative epithelium; 1:400 leaves the weak-positive cells unstained. All other conditions are identical. The technologist needs 6.0 mL at the dilution with the best acceptable sensitivity and specificity. Which preparation should be made?
Correct answer: B - 30 µL of concentrate plus 5,970 µL of diluent
HER2 staining in an invasive breast carcinoma is intense and completely circumferential in a contiguous focus comprising 5% of the invasive tumor. The remaining invasive cells are unstained. The focus is not ductal carcinoma in situ, and the controls are satisfactory. Under the ASCO/CAP breast algorithm, how should this pattern be handled?
Correct answer: C - Score 2+ and proceed to reflex in situ hybridization
A core biopsy of a lung nodule contains a gland-forming carcinoma. Tumor cells show nuclear TTF-1 and PAX8, strong cytoplasmic thyroglobulin, and no Napsin A. Each stain has appropriate controls. Which line of differentiation is most strongly supported by the panel rather than by the biopsy site alone?
Correct answer: D - Thyroid follicular-cell differentiation
While transferring 10% neutral buffered formalin, a technologist splashes the solution into one eye. A functioning eyewash is immediately accessible, and a coworker is present to summon assistance. What must happen first?
Correct answer: D - Begin continuous irrigation at the eyewash immediately
A new lot of an established nonpredictive antibody arrives from the same vendor with the same clone and formulation. The laboratory changes no assay conditions. A documented comparison with the accepted lot includes weak-positive, strong-positive, and negative tissues; all meet the approved acceptance criteria, and the required review is complete. Which disposition is appropriate?
Correct answer: A - Accept the new lot and continue routine quality control
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