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.

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. 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. 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%. 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.

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