Morular Metaplasia of the Endometrium: A Case Report and Literature Review: Care Pathways based on Molecular Biology

Abstract

Background: Endometrial morular metaplasia, a clinical conundrum from a diagnostic and management angle given its rarity and low oncogenic potential has been linked to endometrial hyperplasia and carcinoma. Case report: A 77-year-old woman with no significant past medical history was found to have an asymptomatic thickened endometrium on pelvic imaging, after presenting with lower abdominal pain, 3 yrs ago. Diagnostic hysteroscopy identified an endometrial polyp within a pyometra. Histopathology showed focal complex hyperplasia without atypia with superimposed morular metaplasia (EMM) amongst negative microbiology. Following conservative management with a Multidisciplinary Team (MDT) overview, as per her choice with 6-monthly follow-up hysteroscopies, endometrial biopsies, and a short use of the Mirena IUS (discontinued due to poor tolerance), histopathology shows resolved hyperplasia with persistent EMM. She is considering a hysterectomy. Discussion: Current evidence suggests that a sub-type of EMM, a likely histological manifestation of beta-catenin (CTNNB1) gene mutation: could be a precursor of endometrial hyperplasia and low-grade endometrioid-endometrial carcinoma sub-type. Though low-grade in nature, the increased recurrence risk raises significant concerns. Management options which include conservative, hormonal, and surgery have been described in the literature. A few cases of premenopausal women have been managed conservatively, with one resulting in a pregnancy. However, due to the lack of a natural history timeline, the optimal frequency of endometrial sampling when uterine-sparing, is unclear, leading to a management conundrum. Conclusion: Management of morular endometrial metaplasia can be difficult but must reflect the woman’s choice with an MDT overview. Immuno-histochemical tools utilizing new molecular biological advances can simplify the diagnostic and prognostication processes, aiding clinical management.