Endometrioid Borderline Tumour of the Ovary: Pathological Analysis of a Rare Case

Endometrioid Borderline Ovarian Tumours (EBOTs) are rare epithelial tumours with low malignant potential, also referred to as atypical proliferative endometrioid tumours. EBOTs exhibit glandular proliferation and nuclear abnormalities without invading surrounding tissue, which distinguishes them from invasive endometrioid carcinomas. The endometrioid subtype represents a rare category of Borderline Ovarian Tumours (BOTs). We present a case of a 45-year-old woman who had a right ovarian haemorrhagic cyst discovered during a routine ultrasound. The diagnostic workup included a pelvic Magnetic Resonance Imaging (MRI) scan, which showed a complex ovarian cyst with solid components, suggesting a neoplasm. Serum tumour markers, including Cancer Antigen (CA)-125, Carcinoembryonic Antigen (CEA), and CA 19-9, were all normal. Given the imaging results and clinical analysis, the patient underwent a Total Laparoscopic Hysterectomy (TLH) along with a Bilateral Salpingo-Oophorectomy (BSO). Histopathological Examination (HPE) of the removed ovary revealed glandular proliferation lined by stratified columnar cells with mild to moderate nuclear atypia and no stromal invasion. Immunohistochemistry (IHC) supported the diagnosis by showing positive results for Estrogen Receptor (ER), Progesterone Receptor (PR), and Cytokeratin 7 (CK7) with a lower proliferation index (Ki-67), which helped rule out invasive carcinoma and similar conditions. This case emphasises the need for a thorough diagnostic process, including imaging, tumour markers, HPE, and IHC for accurate classification. While EBOTs are less aggressive, careful pathological interpretation is necessary to prevent misdiagnosis and unnecessary treatment. Ongoing clinical monitoring is important due to the potential for recurrence or progression. Recognising EBOTs as a separate group allows for better patient management and improved outcomes.