Sentinel lymph node labeling of patients with deep infiltrating rectovaginal endometriosis - does this make sense?

Purpose: Deep infiltrating endometriosis is a chronic disease of largely unresolved pathogenesis. Lymphatic dissemination of endometriotic cells has been shown in incidentally removed mesorectal lymph nodes (ILNs) and in pelvic sentinel lymph nodes (SLNs) but its significance is unknown. To evaluate this observation further, we compared occurrences and morphology of endometriotic lesions (EM-lesions) within pelvic SLNs with those within ILN. Methods: From 18 patients, 58 pelvic SLNs and from additional 23 patients 105 ILNs, found in the resection specimens, were excised. All lymph nodes were examined for possible endometriotic lesions. Detection of endometriotic lesions were performed by immunohistochemical analysis of possible expression of estrogen and progesterone-receptors as well as CD10 and cytokeratin. Furthermore, two dimensional sizes of endometriotic lesions were measured. Results: Endometriotic lesions were found in 14 patients: in 6 patients of the SLN-group (33%) and in 8 patients of the group of incidentally removed lymph nodes (28%). EM-lesions of the SLN-group were significantly larger than those of incidentally removed regional LN (size A: p= 0.014; size B: p= 0.006). Conclusion: Detection of endometriotic lesions in SLNs and in ILNs has demonstrated lymphatic dissemination of endometriosis. In comparison to the incidentally excised lymph nodes of patients with rectovaginal endometriosis, the sentinel lymph node concept is much more suitable for detection of potentially affected lymph nodes. Therefore, we postulate use of this system in future studies to evaluate the clinical significance of lymphatic dissemination of endometriotic cells.