A rare case of bilateral adnexal Müllerian adenosarcoma arising from endometriosis: A case report and literature review

Background Müllerian adenosarcoma is an uncommon mixed epithelial–mesenchymal neoplasm that predominantly develops in the uterine corpus and rarely occurs in extrauterine sites, including the ovary. Ovarian adenosarcoma is associated with a more aggressive course and is often linked to endometriosis. Case presentation We present the case of a nulliparous woman in her early 30s who presented with abdominal bloating, pelvic pain, and significant ascites. Imaging studies revealed bilateral adnexal solid–cystic masses. Histopathologic and immunohistochemical (IHC) evaluation of the resected specimens demonstrated Müllerian adenosarcoma involving both adnexa and peritoneal surfaces, likely arising from endometriosis. Conclusion This case highlights the diagnostic difficulty of extrauterine Müllerian adenosarcoma, particularly when presenting as bilateral adnexal Müllerian adenosarcoma with peritoneal involvement arising in the setting of endometriosis. Detailed histopathologic evaluation is essential, especially when glandular elements show mucinous differentiation, which broadens the differential diagnosis.