Evaluating triage protocols for endoscopic ultrasound-guided fine needle biopsies of the pancreas

Pancreatic endoscopic ultrasound-guided fine needle biopsy (EUS-FNB) acquires both direct smear and small core biopsy specimens. The triage protocols for pancreatic FNBs to cytopathology (CP) or gastrointestinal surgical pathology (GIP) are controversial and vary by institution.

Pancreatic EUS-FNBs obtained with the SharkCore FNB were reviewed from January 2014 to June 2019. The specimen characteristics and pathology data, including tissue triage, were obtained from the electronic medical records. We assessed the diagnostic yield, defined as malignant, specific neoplastic, or benign, and the operating characteristics at the time of rapid on-site evaluation (ROSE) and final diagnosis.

We reviewed 324 pancreatic FNBs from 313 patients. Of the 324 FNBs, 260 (80%) obtained concurrent direct smear and core biopsy specimens, 30 (12%) of which were divided between CP and GIP. Of the 51 core-only specimens, 47 (92%) were reviewed by CP and 4 (8%) by GIP. ROSE improved the overall diagnostic yield by 10% and accuracy by 9%. When core specimens were reviewed independently, the diagnostic accuracy was 93% for CP (n = 248) and 100% for GIP (n = 33). All false-negative results of the CP-reviewed cores were due to sampling error. Concurrent smear review improved EUS-FNB performance, increasing the negative predictive value by 10% and accuracy by 3% compared with core review alone.

CP and GIP can accurately interpret pancreatic EUS-FNB specimens. However, triage of concurrent EUS-FNB-acquired smear and core specimens to CP may be most efficient as CPs are trained to assess adequacy at the time of ROSE, as well as interpret all parts of the biopsy, minimizing the risk of discordant pathology reports.