Lymphatic spread of endometriosis to pelvic sentinel lymph nodes: a prospective clinical study

Objective: To establish the prevalence of endometriosis metastatic to pelvic sentinel lymph nodes (PSLN) in women with ovarian and/or peritoneal endometriosis.

Design: Prospective clinical study.

Setting: Academic research institution.

Patient(s): Women with a laparoscopic diagnosis of ovarian and/or peritoneal endometriosis verified by intraoperative frozen section analysis.

Intervention(s): Resection of endometriotic lesions and PSLN after cervical blue dye injection.

Main outcome measure(s): Histologic analysis of PSLN for the presence of endometriosis and immunohistochemical analysis of estrogen receptor (ER), progesterone receptor (PR), cytokeratin (CK), and CD-10 expression.

Result(s): The study enrolled 26 women with suspected endometriosis; endometriosis was confirmed in 23 women, and a PSLN was identified in 19 women. A total of 37 (right side: 20; left side: 17) lymph nodes were removed. The prevalence of endometriotic lesions in PSLN was 11% (2 of 19). Both lesions were positive for ER, PR, CK, and CD-10. Isolated endometriotic-like cells (IELCs) staining positive for ER and PR were identified in the peripheral sinus of 16 (80%) of 20 and 14 (70%) of 20 PSLN, respectively. All IELCs lacked CK staining, whereas CD-10 staining was present in 16 (80%) of 20 cases, indicating a stromal origin of IELCs. Intraoperative and/or postoperative complications were observed in 1 (5%) of 19 women.

Conclusion(s): Spread of IELCs to PSLN is common in ovarian and/or peritoneal endometriosis. Metastatic lesions in PSLN are present in 11% of women. Further studies to evaluate the prognostic and predictive value of endometriotic spread to PSLN are warranted.