CytoRich Red–based specimen processing is associated with improved histologic diagnostic performance in EUS-Guided tissue acquisition for pancreatic tumors: A retrospective before-and-after study

Background Conventional specimen processing during endoscopic ultrasound-guided tissue acquisition (EUS-TA) may reduce tissue available for histologic assessment when part of the specimen is allocated to rapid on-site evaluation. CytoRich Red (CR)-based processing permits cytologic assessment after tissue-core retrieval. Aims We evaluated whether CR-based processing was associated with improved histologic diagnostic performance in EUS-TA for pancreatic tumors. Methods This retrospective before-and-after study included patients undergoing EUS-TA from February 2014 to March 2026. Conventional processing was used through September 2020, followed by CR-based processing. The primary 22-gauge analysis compared conventional fine-needle aspiration (FNA), CR-FNA, and CR fine-needle biopsy (FNB). The primary outcome was the correct histologic diagnosis rate. Logistic regression evaluated histology–final diagnosis discordance. Results Of 325 patients, four without an established final diagnosis were excluded. The 22-gauge cohort comprised 228 patients: conventional FNA, 64; CR-FNA, 85; and CR-FNB, 79. Correct histologic diagnosis rates were 78.1%, 94.1%, and 91.1%, respectively (P = 0.010), and were higher with CR-FNA (Holm-adjusted P = 0.011) and CR-FNB (Holm-adjusted P = 0.034) than with conventional FNA. CR-FNA (adjusted odds ratio [OR], 0.198; 95% confidence interval [CI], 0.066–0.597) and CR-FNB (adjusted OR, 0.285; 95% CI, 0.103–0.785) were associated with lower odds of discordance. In the overall cohort, CR use was associated with lower odds of discordance (adjusted OR, 0.258; 95% CI, 0.124–0.536). Comprehensive genomic profiling yielded reportable results in 16 of the 18 selected CR-processed specimens. Conclusions CR-based processing was associated with improved histologic diagnostic performance in pancreatic EUS-TA.