ESSENTIALS AND TIPS FOR EUS-FNA FOR GASTRIC SUBEPITHELIAL LESION

Abstract

EUS-FNA is now widely performed to obtain pathological specimens of gastric subepithelial lesion (SEL). EUS-FNA of gastric SEL is mainly performed on mesenchymal tumors such as gastrointestinal stromal tumors (GIST), and requires a sufficient size of specimen for immunohistochemistry. However, specimens from the gastric SEL may be difficult to obtain using EUS-FNA for the following reasons: the lesion often escapes with the gastric wall during the puncture, or the lesion itself is hard and difficult to puncture. Therefore, it is important to devise new aspiration methods such as the slow pull technique and wet suction technique, which have been gaining attention in addition to basic puncture methods such as the door-knocking method and fanning technique. Despite these methods, obtaining a sufficient amount of specimen of gastric SELs has been difficult. Recently, the fine-needle biopsy (FNB) needle and the forward-viewing linear echoendoscope have appeared as revolutionary developments. The FNB needle is a needle with a tip shape designed to enable collection of specimens of adequate quantity and quality. This has recently led to reports that sufficient quantity and quality specimens could be obtained even in SELs of less than 20 mm. In addition, the forward-viewing linear echoendoscope allows for the lesion to be easily approached. Therefore, its usefulness has been reported even for lesions in the greater curvature of the gastric body, where specimen collection has been difficult until now. Furthermore, rapid on-site cytological evaluation (ROSE) is useful in determining whether evaluable specimens have been collected, but it has been reported that a sufficient amount of specimen can be collected without ROSE when an FNB needle is used. It is expected that the diagnostic ability of EUS-FNA in gastric SEL will be improved by further development of equipment and techniques.