QIHC study guide
QIHC · Work through your exam, one topic at a time.
The Qualification in Immunohistochemistry (QIHC) is a professional credential offered by the ASCP Board of Certification for laboratory professionals who perform, supervise, or interpret immunohistochemical testing. It is a voluntary qualification rather than a license: it signals that a technologist, histotechnologist, or laboratory supervisor has demonstrated knowledge beyond routine procedure-following - the reasoning behind why a protocol works and what to do when it does not. The QIHC study guide has 7 sections and about 2,581 words.
01Preanalytic Variables and Specimen Handling: Fixation, Processing, Sectioning, and Antigen Preservation
No antibody can rescue a specimen that was allowed to autolyze, dry out, or over-fix. The candidate must be able to trace the entire chain: warm ischemia at procurement, cold ischemia time (time from excision to fixative, ideally under 1 hour), fixative choice (neutral buffered formalin 10% is the standard; alcohol-based fixatives preserve DNA but alter many protein epitopes), fixative pH and osmolarity, fixation duration, gross section thickness, processing solvents, embedding, section thickness, and slide storage.
407 words, about 2 min02Antigen Retrieval and Pretreatment: Heat-Induced and Enzymatic Methods, Buffer Selection, and Optimization
Formalin cross-links proteins and masks epitopes. Retrieval reverses or exposes them and is often the single largest determinant of staining quality.
386 words, about 2 min03Staining Methods and Detection Systems: Direct/Indirect, Polymers, Amplification, Chromogens, and Multiplexing
Direct methods label the primary antibody; indirect methods use an unlabeled primary followed by a labeled secondary, gaining signal amplification. Modern routine IHC is usually a two-step polymer: a secondary antibody or compact polymer bearing horseradish peroxidase (HRP) or alkaline phosphatase (AP) and a small-molecule antibody.
372 words, about 2 min04Controls, Validation, and Quality Assurance/Quality Control
The candidate must distinguish four controls. A positive tissue control is tissue known to express the antigen and confirms the whole reagent chain worked.
361 words, about 2 min05Interpretation, Localization Patterns, and Reporting
Before calling anything positive, decide which compartment should stain. Nuclear markers (ER, PR, Ki67, p53, TTF-1, PAX8, SOX10) must show nuclear staining; cytoplasmic markers (cytokeratins, synaptophysin, CD68, most intermediate filaments) stain the cytoplasm; membranous markers (HER2, CD20, CD3, E-cadherin) require crisp membrane staining.
324 words, about 2 min06Troubleshooting and Problem Solving: Background, Weak or Absent Staining, and Edge Artifacts
Every troubleshooting algorithm begins with the positive control. If the positive control is negative, the problem is technical: expired or mishandled reagent, failed detection, forgotten retrieval, or an instrument fault.
361 words, about 2 min07Safety, Regulatory, and Laboratory Operations
The IHC laboratory handles formalin (a known carcinogen and sensitizer), xylene and other aromatic solvents, DAB (a suspected carcinogen), hydrogen peroxide, and concentrated acids and bases. Requirements include a functioning chemical fume hood, appropriate gloves and eye protection, spill kits, and segregated waste streams for formalin and solvent.
370 words, about 2 min