Endoscopic ultrasound-guided fine needle aspiration in submucosal lesion

A submucosal lesion, more appropriately a subepithelial lesion, is hard to diagnose. Endoscopic ultrasonography is good to differentiate the nature of submucosal lesion. For definite diagnosis, tissue acquisition from submucosal lesion is necessary, and many methods have been introduced for this purpose mainly by endoscopic ultrasonography, such as endoscopic ultrasound-guided fine needle aspiration (EUS-FNA), EUS-guided Trucut Biopsy (TCB), and EUS-guided fine needle biopsy (FNB). For EUS-FNA, adequate processing of specimen is important, and for proper diagnosis of EUS-FNA specimen, both cytologic and histologic examinations, including immunohistochemical stains, are important. All gastrointestinal stromal tumors have some degree of malignant potential, so there have been a lot of efforts and methods to increase diagnostic yields of submucosal lesion. We herein review the current hot topics on EUS-FNA for submucosal tumor, such as needles, on-site cytopathologists, immunohistochemical stains, EUS-TCB, EUS-FNB, Ki-67 labelling index, DOG1, and combining EUS-FNA and EUS-TCB.