ENDOSCOPIC ULTRASONOGRAPHIC DIAGNOSIS OF GASTROINTESTINAL SUBMUCOSAL TUMORS

Abstract

Gastroenterologists often encounter patients with a gastrointestinal submucosal tumor. This type of tumor is defined collectively as a protruding mucosal area raised by a subepithelial lesion. Submucosal tumors are often difficult to diagnose because first, the lesion usually cannot be observed endoscopically and, second, the tumor consists of varying tissues. Therefore, endoscopic ultrasonography (EUS) is considered useful for diagnosing submucosal tumors. EUS methods can be broadly divided into two methods, one using an ultrasound gastrovideoscope and the other using an ultrasound probe, the latter of which is usually passed through the instrument channel of a standard endoscope. In either method, high-quality imaging is required to perform a detailed diagnostic examination. Hence, selecting the appropriate device and imaging method is key. Submucosal tumors such as a lipoma, aberrant pancreas, cyst, and lymphangioma can usually be diagnosed by standard endoscopy or the EUS procedure because the characteristic findings of such tumors can be observed on EUS. Therefore, biopsy sampling is considered unnecessary in the diagnosis of these submucosal tumors. Meanwhile, it is often difficult to make a diagnosis by EUS when a hypo- or irregular-echoic lesion is observed in the submucosal layer or the muscularis propria. To make a definitive diagnosis of this type of lesion, pathological examination of biopsy samples is recommended. While biopsy samples from the lesion can be collected using various methods such as EUS-guided fine needle aspiration and unroofing techniques, diagnostic imaging must be improved through the development of new diagnostic techniques.