Endoscopic ultrasound (EUS) is a combination of endoscopy and intraluminal ultrasonography. EUS also enables ultrasonographic images of high resolution to be obtained. However, whether a lesion is malignant or benign cannot be diagnosed solely from the findings of EUS. Endoscopic ultrasound-guided fine-needle aspiration biopsy (EUS-FNAB) was developed to enhance the diagnostic capabilities of EUS by providing additional pathological findings.