Case-specific, in vivo identification of lymph node drainage from the peritoneal space

Abstract

Background. Demonstration of lymph node metastasis in the setting of malignant ascites could assist in staging and treatment of ovarian, endometrial, and colon cancer. The pleural space drains to a sentinel lymph node (SLN) group in the superior mediastinum. The purpose of this study was to determine whether the peritoneal space also drains to a SLN group. Methods. Twelve rats received intraperitoneal injection of quantum dots (QDs), a NIR fluorescent lymph tracer designed for retention in the SLN. Twelve rats received intraperitoneal injection of HSA800, a smaller diameter, NIR lymph tracer designed for uptake into distant lymph nodes. A custom imaging system detected NIR fluorescence at 10 and 30 min and 24 h after injection. Associations were assessed with paired Student’s t-test. Results. QDs identify at most one node, while HSA800 was able to identify multiple nodes ( P = 0.017) (Table 1). QDs drained to either celiac, periportal, or superior mesenteric lymph nodes. After 24 h, HSA800 appeared in these and distant lymph node groups such as the superior mediastinum (Fig. 1). Conclusion. QDs drained to either the celiac, the periportal, or the superior mesenteric region, suggesting a varied SLN drainage. HSA800 traveled as far as the superior mediastinal nodes, suggesting a widespread lymphatic drainage. An advantage of NIR fluorescence imaging is the ability to identify lymph nodes draining the peritoneal space regardless of location. Developing such a patient-specific method of peritoneal SLN mapping could influence staging and treatment in the setting of malignant ascites.