The application of miniprobe ultrasonography in the diagnosis of colorectal subepithelial lesions

Background: Difficulty with the proximal lesion approach and durability of endoscopic ultrasonography (EUS) instruments usually limits its application for lower gaotrointestina (GI) lesions to locoregional staging of rectal cancer. This study investigated the value of colonoscopic miniprobe ultrasonography for differential diagnosis and treatment strategy in patients with colorectal subepithelial lesions (SEL). Methods: Miniprobe ultrasonography was Performed in 40 consecutive patients with suspected colorectal SEL or residual lesions after endoscopic resection at one medical center by the same endoscopist (C-J Lin). The EUS images and procedure records were reviewed. The final diagnosis of these lesions was confirmed by crosssection imaging, histopathologic findings, or clinical follow-up. Results: Miniprobe EUS allowed high-resolution imaging and a successful approach to all colorectal SEL through the working channel of a sigmoidoscope or colonoscope without breakdown of the miniprobe. Thirteen patients, suspected of having rectal carcinoid tumors (mean size, 6.9± 3.3 mm), were treated radically by endoscopic mucosal resection using a transparent cap (EMRC) after EUS confirmation of no muscular invasion. Three patients had no residual or recurrent carcinoid tumor on EUS examination after previous empiric polypectomy or biopsy. EUS detected submucosal lipomas (mean size, 18.5 mm; range, 8.6-25.6 mm) in ten patients however, only two patients underwent endoscopic resection. Five patients had suspected rectal myogenic stromal tumors on EUS; three were transferred for surgical resection due to uterine myoma compression (N = 2) or mucinous adenocarcinoma of the appendix with rectal metastasis (N = 1), and two had uterine myoma detected by gynecologic ultrasound or CT. One appendiceal stone with orifice obstruction mimicking cecal submucosal tumor was proved by surgical resection.One patient had hemorrhoids proved by hemorrhoidectomy. One patient was proved to have proctitis cystica profunda by EMRC. The other six patients had various benign lesions, which were diagnosed and followed-up by EUS without progression. In thirty-five of forty patients (88%) colorectal SEL were managed uneventfully according to EUS interpretation. Conclusions: Miniprobe ultrasonography can be a useful supplement to routine colonoscopy and provide treatment guidance for suspected colorectal subepithelial lesions.