Objectives: Mirena® has been shown to improve symptoms in women with minimal to moderate endometriosis. The precise mechanisms for this have not been thoroughly investigated. We investigate here one possible mechanism-alteration in the number of mast cells in the endometriotic tissue.
Study design: Tissues (endometrial, endometriotic and normal peritoneal biopsies) prospectively collected from twenty-eight women with laparoscopically confirmed minimal to moderate endometriosis before and 6 months after treatment with Mirena® were processed for immunohistochemistry for ER and PR expression followed by toluidine blue staining for mast cells. Photographs were obtained and the receptors and mast cells identified and quantified.
Results: The mean (± SEM) age of the twenty-eight women was 31 (±7.2) (range 18-42) years. Eight of the endometrial biopsies were in the proliferative phase and twenty in the secretory phase. Six months after Mirena®, the number of mast cell expressed in the tissues decreased significantly in the eutopic (P=0.0358) and ectopic endometrium (P=0.0220) but not in the normal peritoneum (P>0.05). There were no ERs or PRs found in mast cells.
Conclusion: Mirena® causes a reduction in mast cell numbers in ectopic and eutopic endometrium in women undergoing symptomatic treatment of minimal to moderate endometriosis. This reduction could partly explain the efficacy of Mirena® in modulating pain in these women.
Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.