Su1315 DIFFERENCES IN THE DIAGNOSTIC YIELD BETWEEN EUS GUIDED FINE NEEDLE ASPIRATION (FNA) AND CORE BIOPSY (FNB) NEEDLES IN THE EVALUATION OF SUBEPITHELIAL LESIONS IN THE UPPER GASTROINTESTINAL TRACT

Abstract

Establishing the histological diagnosis of subepithelial lesions (SEL) can be challenging. Even with rapid on-site cytology (ROSE), the diagnostic yield of EUS-FNA is low (40-65%) as core tissue is often required for ancillary studies such as immunohistochemistry (IHC) stain. Newer EUS-FNB needles are designed to obtain core tissue. This study aimed to compare the diagnostic yield of conventional FNA needles with the newer FNB needles in EUS guided tissue acquisition of SEL in the upper gastrointestinal tract. A prospectively collected database on all patients who were referred for EUS guided tissue acquisition of SEL in the upper GIT over 10 years was retrospectively reviewed. All EUS FNA/FNB procedures were performed without ROSE, and all material from the needles were placed into formalin for direct histological examination. The conventional group included specimens obtained from the 22G and 25G FNA needles and 25G reverse bevel needle. The FNB group included specimens from the 20G or 22G reverse bevel needle. The final diagnosis was based on either surgical specimens or from repeat FNA or FNB specimens with at least 6 months of clinical follow up. Specimens from 178 SEL taken from 166 patients, of which 100 were by FNB needles and 78 by FNA needles. There were no differences in demographics, lesion size and location of the lesion along the upper GIT tract between the group. The needle caliber used in each group as well as the diagnoses are summarized in Table 1. The diagnostic accuracy (86/100 vs 45/78; P<0.001) and ability of perform IHC (70/100 vs. 28/78; P<0.001) were substantially higher with FNB than FNA needles. The number of passes were similar in both groups (FNB=2.2± 0.8 vs 2.3±0.9; P=0.61). Of the non-diagnostic cases (n=47), 29 (61%) were smaller than 15mm, and were suspected to be lipomas (n=22), leiomyomas (n-18), pancreatic rest (n=5) or duplication cysts (n=2) based on EUS evaluation. No patients reported or were re-admitted due to pain, bleeding or perforation. Even with a similar number of needle passes and no ROSE, FNB needles achieved a higher diagnostic accuracy than FNA needles for EUS guided tissue acquisition of SEL, suggesting that FNB is the needle of choice for SEL.