Side-beveled fine needle biopsy needles improve positive cytology rate in endoscopic ultrasound-guided sampling of pancreatic solid lesions

Abstract

Background and Objectives:In the perspective of improving accuracy of endoscopic ultrasound (EUS)-guided sampling, the efforts of innovation have focused on needle design, with the development of micro-core acquisition technology, and puncture technique variations. Available studies have shown that fine needle biopsy (FNB) needles can achieve a satisfactory diagnostic yield after fewer passes when compared to fine needle aspiration (FNA) needles, without an overall diagnostic advantage. Limited data are available to explain these results. We compared FNA and side-beveled FNB needles for micro-core/cellular material retrieval and diagnostic performance in pancreatic solid lesions.Methods:This was a single-center retrospective study of 110 consecutive patients who underwent EUS-sampling for a solid pancreatic lesion. All cellular material was collected for cell-block construction. The cytological examination was performed according to Papanicolaou. KRAS analysis was used as an ancillary technique to resolve indeterminate cases. Sensitivity and specificity were calculated in FNA (EchoTip® Ultra) and in FNB (EchoTip ProCore®) categories. All cases were evaluated for cellularity and micro-core (fragment retaining tissue architecture) retrieval. We compared FNA and FNB needles of different diameter (FNA: 19, 22, and 25G and FNB: 20, 22, and 25G), as well as large (19–20G) and small bore needles (22–25G).Results:Considering only positive cytology as diagnostic for malignancy, FNB needles showed higher sensitivity than FNA needles (86.4% vs. 54.9%, P = 0.002). If KRAS-mutated indeterminate cases were considered as malignant, overall sensitivity was 94.7%. In subcategories (FNB vs. FNA), sensitivity was 97.7% versus 92.2%, P = 0.37. Micro-cores were present in 65.2% of FNB versus 15.1% of FNA samples (P < 0.0001), rising to 95.2% in 20G-FNB category, and in 88.5% of large bore versus 20.5% of small bore needles (P < 0.0001). Considering the overall amount of cellular material (micro-cores plus cellular aggregates), FNB needles were better than FNA (91.3% vs. 62.3%, P = 0.001). The needle diameter did not influence the overall amount of cellular material retrieval since a satisfactory amount could be retrieved in both categories (large vs. small bore needles: 88.5% vs. 71.2%, P = 0.063).Conclusions:FNB needles allowed a relevant improvement in positive cytology with reduced need of KRAS mutational assessment or ancillary techniques. Dedicating all cellular material to the construction of cell-blocks and high retrieval rate of micro-cores may explain these results.