Imaging of endometrial osseous metaplasia—an uncommon but treatable cause of infertility

Abstract Background Endometrial osseous metaplasia (EOM) is an uncommon condition characterised by metaplastic transformation of endometrial tissue into osteoblasts (mature or immature bone in the endometrium). Etiopathogenesis of EOM is explained by multiple putative mechanisms like dystrophic calcification, metaplastic ossification, retained foetal bones after abortions and genito-urinary tuberculosis. EOM has varied clinical presentation ranging from patient being asymptomatic to secondary infertility. Although hysteroscopy is the gold standard for its diagnosis and treatment, non-invasive imaging comprising chiefly of ultrasonography (USG) is increasingly becoming the mainstay of diagnosis. We aim to present the imaging findings in EOM to acquaint radiologists and gynaecologists with this condition to avert misdiagnosis of this uncommon yet treatable cause of infertility. Results Mean age of patients was 31.4 ± 5.4 (S.D) years. USG revealed linear or tubular densely echogenic endometrium with posterior acoustic shadowing in all the 14 patients. MRI in 3 patients revealed diffuse or patchy areas of T1W and T2W hypointense signal intensity with unilateral (n = 2) and bilateral (n = 1) ovarian cysts. One patient who underwent CT scan revealed dense endometrial calcification. Histopathologic examination (HPE) revealed lamellar (n = 6) or trabecular (n = 4) bone within endometrium (EOM) and inflammatory cells with calcification in four patients (calcific endometritis). Twelve patients conceived after dilatation and curettage within 15 months. Conclusion Familiarity with the imaging appearances of EOM is indispensable to clinch this diagnosis and avert misdiagnosis of this rare but potentially treatable cause of infertility. USG is usually sufficient for diagnosis. MRI and CT are only supplementary tools in difficult clinical scenarios.