Huge Ovarian Microcystic Stromal Tumor Presenting As Acute Abdomen in a Patient With Familial Adenomatous Polyposis: A Case Report With Magnetic Resonance Imaging Findings.

Microcystic stromal tumors (MCST) are rare sex cord-stromal tumors with distinctive microcystic features and stromal tumor immunophenotypes. Few reports have discussed MCST from the perspective of magnetic resonance imaging (MRI). In this report, we describe the MRI findings of MCST, review our case, and discuss it based on previous reports. A 24-year-old female with a history of familial adenomatous polyposis (FAP) presented to the emergency department with complaints of lower abdominal pain. A plain abdominal computed tomography scan revealed a huge ovarian tumor measuring 19 cm. MRI revealed an isointense ovarian tumor on T1-weighted images and a heterogeneous high signal intensity on T2-weighted images. Contrast-enhanced MRI demonstrated enhancement confined to the capsular structures. Based on the tumor size and MRI findings, malignancy could not be definitively excluded. However, considering the clinical presentation, a diagnosis of tumor infection was made, and an open adnexectomy was subsequently performed. Pathological examination confirmed the diagnosis of MCST, and the patient's condition progressed without apparent recurrence one year after surgery. In previous reports, MCST has been associated with FAP, and almost all cases were benign. Patients diagnosed with FAP can reduce the risk of acute abdominal pain by using less invasive treatments, as long as they keep up with regular checkups and screenings.