Immunohistochemistry in the workup of bladder biopsies: Frequency, variation and utility of use at an academic center

• Published in: Annals of diagnostic pathology 2019-08, Vol.41, p.124-128
• Main Authors: McIntire, Patrick, Khan, Reema, Kilic, Irem, Wojcik, Eva M., Pambuccian, Stefan E., Barkan, Güliz A.
• Format: Article
• Language: English
• Subjects: Adult; Aged; Aged, 80 and over; Biomarkers, Tumor - analysis; Biopsy; Carcinoma in Situ - diagnosis; Carcinoma in-situ; Carcinoma, Transitional Cell - diagnosis; Female; Humans; Immunohistochemistry; Immunohistochemistry - statistics & numerical data; Male; Middle Aged; Reactive atypia; Urinary Bladder Neoplasms - diagnosis; Urothelial carcinoma; Urothelium
• ISSN: 1092-9134; 1532-8198
• DOI: 10.1016/j.anndiagpath.2019.06.002

Flat urothelial lesions fall into one of four diagnostic categories including urothelial carcinoma in-situ (CIS). There is morphologic overlap between the categories leading to immunohistochemistry (IHC) utilization in difficult cases. The purpose of this study was to examine the frequency, variation and utility of IHC use in bladder biopsy specimens over a 17 year period. A search of “CD44”, “p53”, and “CK20” keywords was conducted from the pathology files (1/1/2003 to 12/31/2017) on bladder biopsy specimens at our institution. Atypical (AUS), dysplastic (UD) and CIS rates were calculated. A total of 4597 cases were identified. IHC was performed on 345 specimens (7.5%, 345/4597). For cases without IHC (H&E only), the AUS rate was 4.8% (206/4252), UD rate was 9.4% (399/4252), and the CIS rate was 8.4% (359/4252). For IHC cases, the AUS rate was 5.2% (18/345), the UD rate was 8.1% (28/345), and the CIS rate was 11.3% (39/345). There was no statistical difference between the H&E only or IHC rates (p > 0.05). The absolute number IHC orders per year increased until 2011 (60 cases) but drastically declined over the last five years (5 total cases in 2017). The CIS rates have remained relatively constant. We found the AUS, UD and CIS rates were similar regardless of IHC use. Our institution was an early adopter of IHC and it quickly fell out of favor. We agree with the ISUP in that IHC has limited clinical utility for flat urothelial lesions and morphology remains the gold standard. •Examined the frequency and utility of IHC in bladder biopsies over 17 year period.•There were 345 specimens (7.5%, 399/4252) in which IHC was ordered.•Atypical, dysplastic and carcinoma in-situ rates were similar regardless of IHC use.•IHC orders have drastically fallen off in last 5 years (only 5 cases in 2017).