Struma Ovarii: Radiological Features and Diagnostic Challenges.

Struma ovarii is a rare monodermal variant of ovarian mature teratoma characterized by the predominance of thyroid tissue, accounting for a small fraction of ovarian germ cell tumors. It demonstrates a highly heterogeneous radiological appearance reflecting its complex internal composition. This variability results in overlapping imaging features with other ovarian tumors, often leading to diagnostic uncertainty in preoperative assessment. This article summarizes the multimodality radiological characteristics of struma ovarii, with emphasis on ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI). Across imaging modalities, struma ovarii typically presents as a complex adnexal tumor with mixed solid and cystic components, heterogeneous internal architecture, and variable enhancement patterns. MRI provides the most distinctive features, including heterogeneous signal intensity on both T1- and T2-weighted sequences, reflecting differing proportions of thyroid tissue, proteinaceous fluid, and hemorrhagic or colloid content. Awareness of the imaging spectrum of struma ovarii is essential for radiologists to improve diagnostic accuracy and guide appropriate clinical management. However, definitive diagnosis is rarely achievable on imaging alone, and histopathological examination remains the gold standard for diagnosis.