Diagnostic efficacy of white core cutoff lengths obtained by EUS-guided fine-needle biopsy using a novel 22G franseen biopsy needle and sample isolation processing by stereomicroscopy for subepithelial lesions

Objectives: The aim of this study is to estimate the cutoff length for stereomicroscopically visible white core (SVWC) required for the pathological diagnosis of subepithelial lesions (SELs) from samples obtained using a novel 22-G Franseen biopsy needle and determine the sensitivity using the SVWC cutoff length. Patients and Methods: Thirty patients with SELs requiring pathological diagnoses were included. EUS-guided fine-needle biopsies (EUS-FNBs) were performed using a novel 22G Franseen biopsy needle. SVWC cutoff lengths were measured using sample isolation processing by stereomicroscopy (SIPS). The utility of the calculated SVWC cutoff lengths was measured. Results: The procedural success and SVWC sampling rates were both 100%. The median SVWC length was 14.5 mm. Pathological examinations identified 16 patients with gastrointestinal stromal tumors, 7 with schwannomas, 6 with leiomyomas, and 1 with an ectopic pancreas. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for diagnosing malignancy using EUS-FNB were all 100%. The final diagnostic accuracy was 100%. Regarding the final diagnosis, based on the receiver operating characteristic curves calculated using the SVWC length, the area under the curve was 0.958 (95% confidence interval: 0.897-1.020, P < 0.001) and the cutoff length was 4 mm. The sensitivity of the new SVWC cutoff length was 98.7%. Conclusions: Diagnostic results of EUS-FNBs using a novel 22-G Franseen biopsy needle were significantly better with SVWC cutoff lengths ≥4 mm. Performing the SIPS procedure with a cutoff value of 4 mm as an index may be especially useful for successful pathological diagnosis of SELs at institutions where rapid on-site evaluation cannot be performed.