Lymphangiogenesis in deep infiltrating endometriosis

BACKGROUND: In patients diagnosed with deep infiltrating endometriosis (DIE), foci of endometriosis are detected in mesorectal lymph nodes (LNs) after segmental bowel resection and in pelvic sentinel LNs. Lymph vessels (LVs) seem to be the possible routes for the dissemination of endometriotic cells from DIE-lesions to LN. Therefore, we conducted a study to investigate the occurrence and density of LV and lymphangiogenic growth factors in DIE. METHODS: Included in this study were 38 premenopausal women who underwent surgery due to symptomatic rectovaginal DIE. In order to identify LV, immunohistochemical analysis with anti-Podoplanin (D2-40), LYVE-1 and Prox-1 was performed. Furthermore, the expression of VEGF-C and VEGF-D in endometriotic tissue was investigated. RESULTS: LV density (LVD) of DIE lesions was significantly higher compared with healthy corresponding tissue. All LV makers could be detected, and the density of LYVE-1- or Prox-1-positive LV was significantly higher than that of D2-40-positive LV. Endometriotic epithelial cells and stromal cells showed a moderate to strong VEGF-C and VEDF-D expression. CONCLUSIONS: DIE lesions have lymphangiogenic properties, probably leading to endometriosis-like cells in lymphatic vessels and LNs featuring a loco-regional disease.