Giant Ovarian Leiomyoma Mimicking a Malignant Intra-Abdominal Tumor

BACKGROUND Leiomyoma is a benign gynecological neoplasm most commonly seen in the uterus, while primary ovarian leiomyomas are exceptionally uncommon. These tumors can grow to a large size and undergo degenerative changes, including infarction. Large ovarian leiomyomas with a solid-cystic appearance on imaging can closely resemble malignant ovarian neoplasms, leading to diagnostic uncertainty. We present a case of giant ovarian leiomyoma exhibiting clinical and radiological features closely mimicking those of an ovarian malignancy. CASE REPORT A 68-year-old para 4 woman presented with a four-year history of progressive abdominal distension, which had notably increased over the past two years. A computed tomography (CT) scan of the thorax, abdomen, and pelvis (CT-TAP) revealed a well-defined, lobulated, heterogeneously enhancing, solid-cystic mass, predominantly occupying the left lower abdominal quadrant and originating from the right ovary. Tumor marker analysis showed normal levels of CEA and CA19-9 with a mildly elevated CA-125 level of 51 U/ml. The calculated Risk of Malignancy Index (RMI) was 153, raising suspicion for an ovarian malignancy. In light of these findings, the patient was planned for a total abdominal hysterectomy and bilateral salpingo-oophorectomy (TAHBSO). The intraoperative findings revealed a right ovarian mass measuring 20×20 cm. Histopathological examination confirmed an ovarian leiomyoma with cystic degeneration. CONCLUSIONS The case report demonstrates the preoperative diagnostic challenges associated with giant ovarian leiomyoma, which can result in an unnecessary radical surgical procedure. This underscores the importance of meticulous preoperative and intraoperative assessment to ensure accurate diagnosis and appropriate management.