Macroscopic on-site evaluation of biopsy specimens for accurate pathological diagnosis during EUS-guided fine needle biopsy using 22-G Franseen needle

BACKGROUND AND OBJECTIVES: Measuring a visible core length during macroscopic on-site evaluation (MOSE) can be useful for accurate diagnoses during an EUS-guided fine needle biopsy (EUS-FNB). We aimed to estimate visible core cutoff lengths predictive of a correct diagnosis when using 22-gauge Franseen needles for biopsies from pancreatic masses. MATERIALS AND METHODS: We assessed 77 consecutive patients who underwent EUS-FNB using 22-gauge Franseen needles for pancreatic masses between March 2018 and October 2018. At least two needle passes were performed in all patients, irrespective of the findings on MOSE. The endoscopists measured the visible cores using a ruler during MOSE. The first two passes were analyzed on a per pass basis, and the correlation between visible core lengths and diagnostic accuracy was evaluated. RESULTS: We evaluated 150 needle passes of 75 patients. The accuracy per pass was 92% (138/150). The median length of the visible cores was 15 (range: 0–60) mm and they were significantly longer in the correct diagnosis group than in the incorrect diagnosis group. The accuracy correlated positively with the visible core length. Receiver-operating characteristic curve analysis of the visible core length for accuracy demonstrated an optimal cutoff value of 10 mm. On multivariate logistic regression, visible core lengths >10 mm independently affected the correct diagnosis (odds ratio: 5.1, P = 0.02). CONCLUSIONS: Visible cores exceeding 10 mm may be useful for correct diagnosis while using a 22-gauge Franseen needle for EUS-FNB from pancreatic masses.