Struma ovarii: Diagnostic pitfalls, management strategies, and clinical outcomes from a tertiary medical center

OBJECTIVE: To summarize the clinical, imaging, pathological, and surgical characteristics of struma ovarii and evaluate outcomes from a 17-year single-center experience. MATERIALS AND METHODS: A retrospective review of 35 patients with histologically confirmed struma ovarii treated at Cathay General Hospital between January 2008 and January 2025 was conducted. Clinical data, imaging features, surgical approach, frozen section use, pathology, and follow-up outcomes were analyzed. RESULTS: The mean age at diagnosis was 43.3 years. One-third of patients were asymptomatic; others presented with abdominal pain, distension, or pelvic mass. Mean CA-125 was 51.5 U/mL. Ultrasonography commonly revealed multiloculated cystic masses with heterogeneous echotexture and minimal Doppler flow; several cases exhibited the characteristic "struma pearl sign." Laparoscopic surgery was performed in 60% of patients, and frozen section in 57%. Pathology showed 18 benign pure, 15 benign impure, and 2 malignant cases with papillary thyroid carcinoma arising within struma ovarii. During a median follow-up of 18 months, no recurrence or metastasis occurred. CONCLUSION: Struma ovarii is a rare ovarian teratoma with variable clinical and imaging presentations. The struma pearl sign, when present, may serve as a supportive sonographic clue, but its absence does not exclude the diagnosis. Frozen section may assist intraoperative decision-making in selected cases, although final diagnosis should rely on permanent histopathological evaluation. Long-term follow-up remains important, particularly for malignant or atypical cases.