ESA-SRB-AOTA 2019

Investigating the heterogeneity of endometriotic lesions (#711)

Eliza M Colgrave 1 , Sophie Bittinger 2 , Leonie Cann 1 , Peter AW Rogers 1 , Janet R Keast 3 , Jane E Girling 4 , Sarah J Holdsworth-Carson 1
  1. Department of Obstetrics and Gynaecology, RWH, The University of Melbourne, Melbourne, Victoria, Australia
  2. Department of Pathology, The Royal Women's Hospital, Melbourne, Victoria, Australia
  3. Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Victoria, Australia
  4. Department of Anatomy, The University of Otago, Dunedin, Otago, New Zealand

Background: Endometriosis is characterised by the presence of endometrial-like lesions outside of the uterus. The presence of endometrial-like glands and/or stroma is the only observation required for a pathologist to diagnose endometriosis. More extensive pathologic phenotyping of lesions may improve diagnosis and treatment decisions. This project aims to characterise a broad range of morphological features in endometriotic lesions in the context of patient medical and phenotypic data (e.g. menstrual cycle stage) to better illustrate the makeup and heterogeneity of endometriotic lesions.

Methods: Endometriotic lesion biopsies (n = 42 patients from across the menstrual cycle, 152 biopsies, 1,069 endometriotic glands) were analysed by brightfield microscopy of haematoxylin and eosin stained sections (independently, by EC (researcher) and SB (pathologist)). A mixed effects logistic regression analysis was utilised to determine if patient variables (e.g. menstrual cycle stage) had a significant effect on the characteristics of the endometriotic lesions.

Results: There was significant inter- and intra-patient variability in the epithelium, stroma and tissue surrounding endometriotic lesions. Some subtle menstrual cycle-associated changes were observed among lesions, including a significant increase in epithelial mitoses in endometriotic glands from proliferative phase patients (18% of glands) compared to menstrual and secretory phase patients (0% and 2% of glands, respectively; OR = 7.26, p<0.001, 95% CI 3.04-17.29). In contrast, there were no significant differences in the proportion of glands with haemosiderin-laden macrophages across the menstrual cycle, indicating signs of haemorrhage were present in lesions independent of menstrual stage (prob > chi2 = 0.13).

Conclusion: We observed some significant changes in endometriotic lesions associated with features of the menstrual cycle, but they were not prominent in all lesions as has previously been proposed. The results of this project provide a foundation for further targeted characterisation of the heterogeneity of molecular features in endometriotic lesions.