Prostate-specific membrane antigen immunostaining in endometriosis: preliminary findings and a case of in vivo imaging with gallium-68 positron emission tomography/computed tomography

Background Endometriosis is a systemic, estrogen-dependent inflammatory disorder affecting approximately 10% of women of reproductive age and is even more common among those with chronic abdominal pain and infertility. Despite research advances, understanding its pathogenesis and distinguishing endometriotic cysts remain challenging. Prostate-specific membrane antigen (PSMA), traditionally used in the imaging and treatment of prostate cancer, has been detected in various benign and malignant conditions. This study evaluated PSMA expression in endometriosis tissues as a marker to differentiate ovarian endometriotic cysts from other cysts.

Formalin-fixed, paraffin-embedded tissue samples from 10 patients with histopathologically confirmed endometriosis who underwent surgery in 2023 were analyzed. Tissue sections were stained with hematoxylin and eosin, and immunohistochemical analysis was performed using an antibody against PSMA. PSMA expression was assessed in microvascular endothelial cells and non-endothelial cells using a semi-quantitative immunoreactivity scoring system. In addition, a case study involving Gallium-68-labeled PSMA positron emission tomography/computed tomography (PET/CT) imaging was conducted in one patient.

PSMA immunostaining was positive in 28 of 33 endometriosis tissue samples. Notably, strong and diffuse PSMA expression was observed exclusively in the microvessels of ovarian endometriotic cyst capsules, with all 11 slides of this subtype demonstrating high vascular expression. In contrast, no PSMA expression was detected in other ovarian cyst types, such as follicular and corpus luteum cysts. Weak PSMA staining in non-endothelial cells was noted in 15 slides, primarily within endometrial glands in cases of scar endometriosis and in fallopian tubes. High vascular PSMA expression was unique to ovarian endometriosis among the three forms evaluated (scar, tubal, and ovarian). Two out of five uterine fibroid samples also exhibited high vascular PSMA expression, while the rest showed low expression. The PET/CT examination confirmed significant tracer accumulation in an ovarian endometriotic cyst.

The study demonstrates that PSMA expression is predominantly localized to the microvessels of ovarian endometriotic cyst capsules, effectively distinguishing them from other ovarian cysts. The limited or absent PSMA staining in non-ovarian endometriosis supports its potential role as a diagnostic marker. These findings warrant further investigation into the utility of PSMA in imaging and possibly therapeutic targeting of ovarian endometriosis. Similar content being viewed by others Data availability The study results were included in this published article. Abbreviations - PSMA: - Prostate–Specific Membrane Antigen - PET/CT: - Positron Emission Tomography/Computed Tomography - TVUS: - Transvaginal Ultrasound - MRI: - Magnetic Resonance Imaging - IHC: - Immunohistochemistry - IRS: - Immunoreactivity Score - TVUS: - BP–Transvaginal Ultrasound with Bowel Preparation - RWC: - TVS–Rectal Water Contrast Transvaginal Sonography - IOTA: - International Ovarian Tumor Analysis - ESHRE: - European Society of Human Reproduction and Embryology - IDEA: - International Deep Endometriosis Analysis - SUVmax: - Maximum Standardized Uptake Value - MIP: - Maximum Intensity Projection - US: - Ultrasound - OEC: - Ovarian Endometriotic CystFC–Follicular Cyst - CLC: - Corpus Luteum Cyst - FT: - Fallopian Tube - PAK: - 1–p21–Activated Kinase 1 - eNOS: - endothelial Nitric Oxide Synthase

Ilangavan K, Kalu E. High prevalence of endometriosis in infertile women with normal ovulation and normospermic partners. Fertil Steril. 2010;93(3):e10. Sapkota Y, et al. Meta-analysis identifies five novel loci associated with endometriosis highlighting key genes involved in hormone metabolism. Nat Commun. 2017;8(1):15539. Becker CM, Bokor A, Heikinheimo O, Horne AW, Jansen F, Kiesel L, King K, Kvaskoff M, Nap A, Petersen K, Saridogan E, Tomassetti C, van Hanegem N, Vulliemoz N, Vermeulen N; ESHRE Endometriosis Guideline Group. ESHRE guideline: endometriosis. Hum Reprod Open. 2022;2022(2):hoac009. https://doi.org/10.1093/hropen/hoac009. Eskenazi B, et al. Validation study of nonsurgical diagnosis of endometriosis. Fertil Steril. 2001;76(5):929–35. van Barneveld E, et al. Depression, Anxiety, and Correlating Factors in Endometriosis: A Systematic Review and Meta-Analysis. J Womens Health (Larchmt). 2022;31(2):219–30. Schliep KC, et al. Pain typology and incident endometriosis. Hum Reprod. 2015;30(10):2427–38. Habiba M, Guo S-W, Benagiano G. Are Adenomyosis Endometr Phenotypes Same Disease Process? Biomolecules. 2023;14(1):32. Nisenblat V, Bossuyt PM, Farquhar C, Johnson NP, Hull ML. Imaging modalities for the non-invasive diagnosis of endometriosis. Cochrane Database Syst Rev. 2016;2:CD009591. https://doi.org/10.1002/14651858.cd009591.pub2. Dunselman G, et al. ESHRE guideline: management of women with endometriosis. Hum Reprod. 2014;29(3):400–12. Sayasneh A, et al. The characteristic ultrasound features of specific types of ovarian pathology. Int J Oncol. 2015;46(2):445–58. Denmeade S. Prostate-Specific Membrane Antigen. Encyclopedia of Cancer. Berlin Heidelberg: Berlin, Heidelberg: Springer; 2011. pp. 3068–72. M. Schwab, Editor. Duraiyan J, et al. Applications of immunohistochemistry. J Pharm Bioallied Sci. 2012;4(Suppl 2):S307–9. Van de Wiele C, et al. PSMA expression on neovasculature of solid tumors. Histol Histopathol. 2020;35(9):919–27. Wernicke AG, et al. Prostate-specific membrane antigen (PSMA) expression in the neovasculature of gynecologic malignancies: implications for PSMA-targeted therapy. Appl Immunohistochem Mol Morphology. 2017;25(4):271–6. Kunikowska J, et al. 68Ga–Prostate-Specific Membrane Antigen-11 PET/CT: A New Imaging Option for Recurrent Glioblastoma Multiforme? Clin Nucl Med. 2020;45(1):11–8. Kunikowska J, et al. 68Ga–Prostate-Specific Membrane Antigen PET/CT in Ovarian Tumors: Potential to Differentiate Benign and Malignant Tumors Before Surgery: A Preliminary Report. Clin Nucl Med. 2023;48(2):e60–6. Klein Nulent TJ, et al. Prostate-specific membrane antigen PET imaging and immunohistochemistry in adenoid cystic carcinoma- a preliminary analysis. Eur J Nucl Med Mol Imaging. 2017;44:1614–21. Tan BF, et al. PSMA PET imaging and therapy in adenoid cystic carcinoma and other salivary gland cancers: a systematic review. Cancers. 2022;14(15):3585. Remmele W, Stegner H. Recommendation for uniform definition of an immunoreactive score (IRS) for immunohistochemical estrogen receptor detection (ER-ICA) in breast cancer tissue. Pathologe. 1987;8(3):138–40. Kennedy S, et al. ESHRE guideline for the diagnosis and treatment of endometriosis. Hum Reprod. 2005;20(10):2698–704. Chapron C, et al. Surgical complications of diagnostic and operative gynaecological laparoscopy: a series of 29,966 cases. Hum Reprod (Oxford England). 1998;13(4):p867–872. Byrne D, et al. Laparoscopic excision of deep rectovaginal endometriosis in BSGE endometriosis centres: a multicentre prospective cohort study. BMJ open. 2018;8(4):e018924. Guerriero S, et al. Deep infiltrating endometriosis: comparison between 2-dimensional ultrasonography (US), 3‐dimensional US, and magnetic resonance imaging. J Ultrasound Med. 2018;37(6):1511–21. Guerriero S, et al. Transvaginal ultrasound vs magnetic resonance imaging for diagnosing deep infiltrating endometriosis: systematic review and meta-analysis. Ultrasound Obstet Gynecol. 2018;51(5):586–95. Moore J, et al. A systematic review of the accuracy of ultrasound in the diagnosis of endometriosis. Ultrasound in Obstetrics and Gynecology. Official J Int Soc Ultrasound Obstet Gynecol. 2002;20(6):630–4. Wykes CB, Clark TJ, Khan KS. Accuracy of laparoscopy in the diagnosis of endometriosis: a systematic quantitative review. BJOG. 2004;111(11):1204–12. https://doi.org/10.1111/j.1471-0528.2004.00269.x. Kuznetsov L, Taylor HJ, Elhussein A, Phillips CJ, Barton-Smith P, Price MJ. Diagnosis and management of endometriosis: summary of NICE guidance. BMJ. 2017;358:j3935. https://doi.org/10.1136/bmj.j3935. Zhang M, Xu T, Tong D, Li S, Yu X, Liu B, Jiang L, Liu K. Research advances in endometriosis-related signaling pathways: A review. Biomed Pharmacother. 2023;164:114909. https://doi.org/10.1016/j.biopha.2023.114909. Anastasiu CV, et al. Biomarkers for the noninvasive diagnosis of endometriosis: state of the art and future perspectives. Int J Mol Sci. 2020;21(5):1750. Gupta D, Hull ML, Fraser IS, Miller L, Bossuyt PM, Johnson NP, Nisenblat V. Endometrial biomarkers for the non-invasive diagnosis of endometriosis. Cochrane Database Syst Rev. 2016;4:CD012165. https://doi.org/10.1002/14651858.cd012165. Liu E, Nisenblat V, Farquhar C, Fraser IS, Bossuyt PM, Johnson NP, Hull ML. Urinary biomarkers for the non-invasive diagnosis of endometriosis. Cochrane Database Syst Rev. 2015;12:CD012019. https://doi.org/10.1002/14651858.cd012019. Nisenblat V, Bossuyt PM, Shaikh R, Farquhar C, Jordan V, Scheffers CS, Mol BW, Johnson NP, Hull ML. Blood biomarkers for the non-invasive diagnosis of endometriosis. Cochrane Database Syst Rev. 2016;5:CD012179. https://doi.org/10.1002/14651858.cd012179. Dessole S, et al. Sonovaginography is a new technique for assessing rectovaginal endometriosis. Fertil Steril. 2003;79(4):1023–7. Takeuchi M, et al. Magnetic resonance imaging characteristics of polypoid endometriosis and review of the literature. J Obstet Gynecol Res. 2022;48(10):2583–93. Valentin L, et al. Risk of malignancy in unilocular cysts: a study of 1148 adnexal masses classified as unilocular cysts at transvaginal ultrasound and review of the literature. Ultrasound Obstet Gynecol. 2013;41(1):80–9. Morgat C, et al. A Vision for Gastrin-Releasing Peptide Receptor Targeting for Imaging and Therapy: Perspective from Academia and Industry. J Nucl Med. 2025;66(8):1160–7. Conway RE, et al. Prostate-specific membrane antigen regulates angiogenesis by modulating integrin signal transduction. Mol Cell Biol. 2006;26(14):5310–24. Gordon IO, et al. Prostate-specific membrane antigen expression in regeneration and repair. Mod Pathol. 2008;21(12):1421–7. Alcázar JL, García-Manero M. Ovarian endometrioma vascularization in women with pelvic pain. Fertil Steril. 2007;87(6):1271–6. Chung MS, Han SJ. Endometriosis-associated angiogenesis and anti-angiogenic therapy for endometriosis. Front Global Women’s Health. 2022;3:856316. Jacobs LF, et al. Evolution of spatial cognition: sex-specific patterns of spatial behavior predict hippocampal size. Proc Natl Acad Sci. 1990;87(16):6349–52. Zhang R, et al. Molecular biomarkers for the early detection of ovarian cancer. Int J Mol Sci. 2022;23(19):12041. Kunikowska J, Bartosz K, Leszek K. Glioblastoma multiforme: another potential application for 68 Ga-PSMA PET/CT as a guide for targeted therapy. Eur J Nucl Med Mol Imaging. 2018;45:886–7.

None. Funding Centre of Postgraduate Medical Education 501-1-022-26-25, 99/103 Marymoncka Street, 01-813 Warsaw, Poland. Author information Authors and Affiliations Contributions All authors were involved in conceiving and designing the study. M. M. prepared the original draft. M.M., M.C., and the team from the Second Department of Obstetrics and Gynecology at the Centre of Postgraduate Medical Education performed the surgeries. Ł. K. conducted PSMA immunostaining and histopathological analysis and prepared Figs. 1, 2, 3 and 4. J.K. and K.P. analyzed PET/CT imaging and prepared figure 5. M.B and M.M. obtained informed consent for additional staining of the material collected from patients during surgery and oversaw patient selection. All authors reviewed and approved the final manuscript. Corresponding author Ethics declarations Ethics approval and consent to participate This study adhered to the Declaration of Helsinki. The research protocol was approved by the Ethics Committee at the Medical University of Warsaw. The analysis was conducted retrospectively, examining histological material from patients who underwent surgery for endometriosis and/or other gynecological conditions. Patients provided standard preoperative consent for the histopathological examination of collected tissues. Additionally, before PSMA analysis and staining, they gave explicit verbal consent for the use of their tissue samples in immunohistochemical research. For the in vivo PET/CT case, a [68Ga]Ga-PSMA-11 scan was performed on a patient with endometriosis confirmed by prior imaging. Ethical approval for PET/CT imaging with PSMA was obtained from the Ethics Review Committee of the Medical University of Warsaw (KB/2/A/2018), and the patient provided written informed consent. Consent for publication Not applicable. Competing interests The authors declare no competing interests. Additional information Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Rights and permissions Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/. About this article Cite this article Martyna, M., Łukasz, K., Michał, C. et al. Prostate-specific membrane antigen immunostaining in endometriosis: preliminary findings and a case of in vivo imaging with gallium-68 positron emission tomography/computed tomography. BMC Women's Health (2026). https://doi.org/10.1186/s12905-026-04380-8 Received: Accepted: Published: DOI: https://doi.org/10.1186/s12905-026-04380-8