Immunohistochemistry in the workup of prostate biopsies: Frequency, variation and appropriateness of use among pathologists practicing at an academic center.
OBJECTIVE
We studied the frequency, inter-pathologist variation, appropriateness and utility of immunohistochemistry (IHC) performed on prostate biopsies (PB) to determine the significance of foci of suspicious glands/atypical small acinar proliferations (ASAP).


METHODS
We calculated the rate of IHC use and diagnostic rate of ASAP and adenocarcinoma in PB from 01/01/2008 to 06/30/2015 for individual pathologists working in a tertiary academic institution, and correlated them with the pathologists' experience, subspecialization and PB volume with the aim of determining the interpathologist variation and appropriateness of use of IHC according to recently published recommendations, and the usefulness of IHC to resolve foci of ASAP as either benign or adenocarcinoma.


RESULTS
IHC was used in 966/2652 (36.4%, 95% CI 33.4-39.4%) PB cases and 1915 of 16,359 (11.7%, 95% CI 11.2%-12.2%) of PB blocks and allowed definitive diagnosis of either benign or malignant in 75.8% (95% CI 73.9-77.7%) of blocks. By pathologist, IHC use rates varied more than twofold (22.8-50.5%); higher use was found for pathologists with genitourinary pathology specialization, higher PB volume and more experience, and correlated with higher rates of both ASAP and adenocarcinoma diagnoses. The use of IHC stains was considered appropriate in 822/966 (85.1%, 95% CI 82.9-87.4%) cases.


CONCLUSIONS
Despite the fact that the use of IHC stains was considered useful and deemed appropriate in the majority of cases, it showed wide variation between pathologists, suggesting monitoring of IHC use rates may be useful to standardize its use.
Department of Pathology, Loyola University Medical Center, Maywood, IL 60153, United States.
Sameer
S
Al Diffalha
Department of Pathology, Loyola University Medical Center, Maywood, IL 60153, United States.
Mohanad
M
Shaar
Department of Pathology, Loyola University Medical Center, Maywood, IL 60153, United States.
Güliz A
GA
Barkan
Department of Pathology, Loyola University Medical Center, Maywood, IL 60153, United States.
Eva M
EM
Wojcik
Department of Pathology, Loyola University Medical Center, Maywood, IL 60153, United States.
Maria M
MM
Picken
Department of Pathology, Loyola University Medical Center, Maywood, IL 60153, United States. Electronic address: spambuccian@lumc.edu.
Stefan E
SE
Pambuccian
D014408:Biomarkers, Tumor / Q000032:analysis*; D001706:Biopsy; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D011467:Prostate / Q000378:metabolism / Q000473:pathology*; D011471:Prostatic Neoplasms / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology*; D015203:Reproducibility of Results; D013194:Staining and Labeling / Q000379:methods
D014408:Biomarkers, Tumor
Atypical small acinar proliferation (ASAP); Immunohistochemistry; Pathologist; Prostate biopsy; Utilization; Variation