Anorectal Neoplasia

Malignant colorectal tumors by endoscopic ultrasound (EUS) appear as hypoechoic masses. Lymph nodes during EUS may be seen as round, oval, or sometimes triangular structures that may be hypoechoic, echogenic, or with mixed echogenicity. Local recurrence of colorectal cancer after attempted curative resection occurs in 2.6-32.0% of patients. Endoscopic ultrasound in such cases may reveal hypoechoic areas outside the colorectal wall. Neoadjuvant chemoradiation is utilized for downstaging of a rectal cancer prior to surgical resection. It is difficult to predict the cause of an endoscopically visible bulge into the gastrointestinal lumen when the overlying mucosa is normal. A lipoma is characterized by a homogeneous echogenic lesion that is contiguous with the third echo layer corresponding with the submucosa. Recurrence of colorectal carcinoma, malignant lymphoma, and appendiceal mucocele may cause submucosal elevation in the colorectum. This chapter contains a large collection of color images obtained from both diagnostic and therapeutic procedures.