Giant Struma Ovarii Mimics Mesenteric Cyst While Causing Acute Intestinal Obstruction

Surgeons have reported the case of a 26-year-old woman with a 15-centimeter struma ovarii accompanied by ovarian torsion and intestinal obstruction that was initially misdiagnosed before surgery as a mesenteric cyst. According to the case report published in BMC Women’s Health, the patient presented with acute abdominal complications and diagnostic challenges that masked the true ovarian origin of the lesion upon initial evaluation by a general surgery service.

Struma ovarii is characterized as a rare monodermal ovarian teratoma composed predominantly of thyroid tissue. Because the clinical presentations and imaging characteristics of struma ovarii are non-specific, the condition is frequently misidentified prior to surgical intervention. Furthermore, the presence of a giant mass combined with torsion, tissue necrosis, and intestinal obstruction represents an uncommon clinical scenario in young female patients, while accompanying ascites and mildly elevated CA-125 tumor marker levels can mimic ovarian malignancy.

The 26-year-old multiparous patient initially sought care after experiencing intermittent right-sided dull abdominal pain over a two-month period alongside a palpable abdominal mass, which subsequently progressed to worsening pain, fever, and incomplete intestinal obstruction. Laboratory assessments demonstrated a marked systemic inflammatory response and mildly elevated CA-125. Preoperative computed tomography scans measured the cystic mass at 164 by 122 by 153 millimeters but misinterpreted the lesion as a mesenteric cyst, whereas a transvaginal ultrasound examination suggested torsion of an ovarian cyst.

An exploratory laparotomy revealed that the patient harbored a giant left ovarian cyst that had undergone torsion and necrosis, along with 300 milliliters of associated ascites. To preserve future reproductive potential, the surgical team performed fertility-sparing surgery via a left partial oophorectomy. An intraoperative frozen section analysis suggested a benign pathology, and subsequent definitive paraffin histological examination confirmed struma ovarii, revealing approximately 55 percent thyroid follicles without other germ cell elements present.

Following the operation, the patient experienced an uncomplicated recovery, with follow-up testing at six months demonstrating that CA-125 levels had normalized and no recurrence had been detected. The authors concluded that struma ovarii should remain an active consideration in the differential diagnosis of young women presenting with large cystic abdominal masses, acute abdominal symptoms, and mildly elevated CA-125, emphasizing that enhanced magnetic resonance imaging and intraoperative frozen sections are valuable tools to prevent overtreatment and protect fertility.

Subject of Research: Misdiagnosis and surgical management of giant struma ovarii presenting with intestinal obstruction

Article Title: A 15-cm struma ovarii with intestinal obstruction misdiagnosed as a mesenteric cyst: a case report

Article References: Wu, S., Wang, Y., Tan, Z., Zhu, J., Chen, Y., Zheng, L., Wang, J., & Li, X. (2026). A 15-cm struma ovarii with intestinal obstruction misdiagnosed as a mesenteric cyst: a case report. BMC Women's Health. https://doi.org/10.1186/s12905-026-05071-0

Image Credits: AI Generated

DOI: 10.1186/s12905-026-05071-0

Keywords: struma ovarii, ovarian teratoma, intestinal obstruction, mesenteric cyst, differential diagnosis, partial oophorectomy, CA-125, case report, struma, ovarii, intestinal, obstruction