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Published on: November 17, 2023
Patterns in immunohistochemical usage in extended core prostate biopsies: comparisons among genitourinary
Anna Plourde1, Alden Gross, Zhong Jiang
1From the Department of Pathology, University of California San Francisco, San Francisco (Dr Plourde); the Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School and the Institute for Aging Research, Hebrew SeniorLife, Boston, Massachusetts (Dr Gross); and the Department of Pathology, University of Massachusetts Medical School, Worcester (Dr Jiang and Dr Owens).
Insights
Genitourinary (GU) pathologists use fewer immunohistochemical (IHC) stains in prostate biopsies compared to non-GU pathologists. This study analyzed IHC utilization patterns in extended core prostate biopsies (ECPBs).
Area of Science:
- Uropathology
- Diagnostic Pathology
- Prostate Cancer Biomarkers
Background:
- Immunohistochemical (IHC) stains are valuable in prostate biopsies, especially for challenging cases.
- Utilization patterns and variations in IHC use among pathologists require further investigation.
Purpose of the Study:
- To compare IHC usage rates between genitourinary (GU) and non-GU pathologists in extended core prostate biopsies (ECPBs).
- To assess the impact of cancer diagnosis, Gleason grade, disease extent, and perineural invasion on IHC ordering rates.
Main Methods:
- Analysis of consecutive ECPBs from 2009-2011 using billing data to quantify IHC stains per case.
- Pathologists were categorized as GU or non-GU based on training and experience.
- Gleason grade, disease extent, and perineural invasion were recorded for cancer cases.
Main Results:
- GU pathologists ordered significantly fewer IHC tests per case and biopsy than non-GU pathologists.
- IHC ordering rates differed most notably for cancerous versus benign lesions.
- High-grade cancer, bilateral disease, and perineural invasion were associated with decreased IHC ordering in both pathologist groups.
Conclusions:
- Genitourinary pathologists demonstrate lower IHC utilization in ECPBs compared to their non-GU counterparts.
- Development of guidelines for appropriate IHC use in prostate biopsies is recommended to standardize workups.
Context:
Immunohistochemical (IHC) stains have known utility in prostate biopsies and are widely used to augment routine staining in difficult cases. Patterns in IHC utilization and differences based on pathologist training and experience is understudied in the peer-reviewed literature.
Objectives:
To compare the rates of IHC usage between specialized (genitourinary; [GU]) and nonspecialized (non-GU) pathologists in extended core prostate biopsies (ECPBs) and the effects of diagnosis; and in cancer cases Gleason grade, disease extent, and perineural invasion on the rate.
Design:
Consecutive ECPBs from 2009-2011 were identified and billing data were used to determine the number of biopsies and IHC stains per case. Diagnoses were mapped and in cancer cases, Gleason grade, extent of disease, and perineural invasion were recorded. Pathologists were classified as GU or non-GU on the basis of training and experience.
Results:
A total of 618 ECPBs were included in the study. Genitourinary pathologists ordered significantly fewer IHC tests per case and per biopsy than non-GU pathologists. The rate of ordering was most disparate for biopsies of cancerous and benign lesions. For biopsies of cancerous lesions, high-grade cancer, bilateral disease, and perineural invasion decreased the rate of ordering in both groups. In cancer cases, GU pathologists ordered significantly fewer stain tests for highest Gleason grade of 3 + 3 = 6, for patients with focal disease and for patients with multiple positive bilateral cores. The effect of the various predictors on IHC ordering rates was similar in both groups.
Conclusions:
Genitourinary pathologists ordered significantly fewer IHC stain tests than non-GU pathologists in ECPBs. Guidelines to define when IHC workup is necessary and not necessary may be helpful to guide workups.

