MLT GlobeHistopathology: Immunohistochemistry & molecular – page 2
28 Histopathology MCQs on Immunohistochemistry & molecular with answers and explanations.
Why is heat-induced epitope retrieval usually needed for IHC on formalin-fixed paraffin sections?
Methylene bridges formed during formalin fixation alter protein conformation and hide epitopes. Heating in buffer breaks these cross-links and restores antibody binding.
Which marker best identifies plasma cells in bone marrow from a suspected myeloma?
CD138 (syndecan-1) is expressed on normal and neoplastic plasma cells. Myeloma cells usually lose CD19 and CD20; CD3 is a T-cell marker.
Which immunostain is used to assess tumor proliferation in breast carcinoma?
Ki-67 is a nuclear antigen present in cycling cells, and the percentage of positive nuclei is the proliferation index. ER, PR and HER2 guide hormonal and targeted therapy.
Which immunostain supports a diagnosis of high-grade squamous intraepithelial lesion of the cervix?
High-risk HPV E7 inactivates RB, causing p16 overexpression; diffuse block staining supports HSIL. Calretinin marks mesothelium and CD34 endothelium.
Reed–Sternberg cells of classic Hodgkin lymphoma are typically positive for:
Classic RS cells express CD30 and CD15 and are usually CD45-negative. CD3 is a T-cell marker, and CD34 marks progenitors and endothelium.
Which immunostain gives a nuclear staining pattern?
Ki-67 is located in the nucleus of proliferating cells. Cytokeratin and vimentin are cytoplasmic filaments, and CD45 is a membrane antigen.
APES (3-aminopropyltriethoxysilane) for coating IHC slides is typically used at what concentration in acetone?
Slides are dipped in about 2% APES in acetone, rinsed and dried, giving a positively charged adhesive surface. Much weaker solutions give poor adhesion.
Which heat-induced retrieval method is often reported to give the strongest results for nuclear antigens such as Ki-67?
Pressure cooking reaches higher temperatures and heats evenly, giving robust unmasking of nuclear epitopes. Low-temperature water baths are gentler but less effective.