Endoscopic ultrasonography in analysing peri-intestinal lymph node abnormality. Preliminary results of studies in vitro and in vivo.

Endoscopic ultrasonography (EUS) was performed on fresh postmortem material, intraoperatively in patients with lymph node abnormality, preoperatively (in vivo), and on corresponding resection specimens (in vitro). Well-defined round or ellipsoid structures adjacent to the intestinal wall, manifesting a more hypoechoic pattern than the surrounding tissues, were interpreted as lymph nodes, which was confirmed by histology. Lymph nodes with an inhomogeneous echo pattern, either similar or more hypoechoic than the pattern of the primary lesions and revealing sharply demarcated borders, were interpreted as highly suggestive of malignancy. In contrast, lymph nodes with a homogeneous but more hyperechoic pattern than that of primary lesions with non-sharply delineated (pseudopoid) boundaries were indicative of inflammatory changes. Small micrometastatic lymph nodes were difficult to detect and often missed. Moreover, lymph nodes that could not be brought adequately into the focus of the ultrasonic beam were not clearly identified. Further studies both in vivo and in vitro, particularly preoperatively and intraoperatively, should be performed to enhance our knowledge and accuracy in interpreting lymph node abnormalities.