Immunohistochemistry Validation Procedures and Practices: A College of American Pathologists Survey of 727 Laboratories
Lindsay B Hardy, Patrick Fitzgibbons, Jeffrey Goldsmith, Richard Eisen, Marybeth Beasley, Rhona Souers, Raouf Nakhleh. Beth Israel Deaconess Medical Center, Boston, MA; St. Jude Medical Center, Fullerton, CA; Greenwich Hospital, Greenwich, CT; The Mount Sinai Medical Center, New York, NY; The College of American Pathologists, Northfield, IL; The Mayo Clinic, Jacksonville, FL
Background: The immunohistochemistry (IHC) lab represents a dynamic area of surgical pathology with limited practice guidelines. Studies have shown significant interlaboratory variability in results. The purpose of this study was to establish baseline parameters for IHC validation procedures and practice, and to assess their feasibility of implementation.
Design: In September 2010, a questionnaire was distributed by the College of American Pathologists (CAP). It was composed of 32 questions relating to non-predictive assays as well as non-FDA approved, predictive IHC assays other than human epidermal growth factor 2 (HER2).
Results: Qualitative aspects of the procedures are shown in table 1. 86% of labs validated the most recently introduced non-predictive antibody. 75% used 21 or fewer total cases for the validation, and 40% used weakly or focally positive cases. 75% of labs validated the most recently introduced predictive antibody other than HER2. Less than half used 25 or more cases for the validation, and 47% used weakly or focally positive cases.
Conclusions: Some laboratories have written validation procedures that appear to build upon HER2 testing guidelines. Some labs also manage to validate new antibodies according to those standards, however many do not. While guidelines for HER2, estrogen receptor, and progesterone receptor help give laboratories some guidance for those IHC procedures, there appears to be a need for further validation guideline development for non-predictive and non-FDA approved predictive antibody assays.
|Percent of laboratories that include in their written procedure:||Non-predictive||Predictive|
|Validation of new antibodies||68||46|
|Specific number of cases required||54||65|
|Revalidation for introduction of a new lot of antibody||66||64|
|Revalidation for introduction or change of antigen retrieval||71||80|
|Revalidation for a change in detection system||74||81|
|Revalidation for a change in instrumentation||74||78|
|Revalidation for a change in fixative||65||74|
|Revalidation for a change in tissue processor instrumentation||49||55|
|Any specifications for use with cytologic material?||37||42|