[2112] Analysis of Immunohistochemical Usage in Different Pathology Practice Settings

Akeesha A Shah, Mark J Mentrikoski, Henry F Frierson, Helen P Cathro. University of Virginia, Charlottesville

Background: Immunohistochemistry (IHC) is a standard diagnostic tool in pathology practice, but the frequency of its use may differ among practice settings. This study analyzes the application of IHC for the diagnosis and classification of carcinoma in several practice types.
Design: Two hundred recent carcinomas (chiefly in biopsies) from patients referred to our institution for treatment were "blindly" and individually reviewed by three of the authors. They included a resident, a mid-level faculty pathologist, and a senior faculty member. The diagnoses, number of cases with IHC stains, and the number of stains performed by the referral pathologists were recorded. To help overcome the inherent bias in the study, a control group of 200 recent consecutive site-matched biopsies performed for cases at our institution were tabulated for the use of IHC stains; these cases were signed-out by pathologists other than those in this study. The referral cases included: prostate (41), endometrium (33), other genitourinary (29), gastrointestinal and hepatobiliary tracts (27), lung (21), head and neck (19), breast (16), other gynecological (11), and bone/soft tissue (3).
Results: Overall diagnostic agreement between study and referral pathologists was 98%. Referral and study pathologists used IHC stains in 26% and 11% of cases, respectively (p < 0.0001). The senior pathologist used stains in 6%, the mid-level pathologist in 14% and the resident in 10% of cases. Pathologists from commercial laboratories (12% of cases from referral practices) used IHC in 38% of cases, while those from private or hospital-based laboratories (86% of referral practice cases) used them in 24%. The mean number of stains used per case by pathologists from private or hospital based laboratories was four, while it was three for those in commercial laboratories, as well as for the study reviewers.
The greatest differences between referral and study pathologists in IHC usage were seen for the following sites: lung (71% vs. 38%) (p=0.06), prostate (27% vs. 5%) (p=0.01), breast (31% vs. 13%), and other gynecological (27% vs. 9%).
For the site-matched control group, the overall IHC rate was 13%. IHC was used for 24% of lung, 17% of prostate, 0% of breast, and 9% of other gynecological cases.
Conclusions: Although diagnostic agreement among pathologists was high, referral pathologists used IHC for more cases than study pathologists. The frequency of use of IHC likely varies for a number of reasons; our study shows that its use reflects, at least in part, the degree of experience of the pathologist as well as the type of pathology practice setting.
Category: Quality Assurance

Monday, March 19, 2012 1:00 PM

Poster Session II # 276, Monday Afternoon


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