A retrospective case series at a tertiary hospital in china: ultrasonographic features of Struma ovarii.

OBJECTIVE

Although struma ovarii (SO) is mostly benign, it is frequently overtreated due to challenges in differentiating it from malignant tumors. Therefore, the purpose of this study was to investigate the clinical, laboratory, ultrasonographic, and pathological characteristics of SO to improve the accuracy of preoperative diagnosis.

METHODS

We retrospectively reviewed the clinical data and imaging characteristics of 103 patients with postoperative pathology for SO at the Affiliated Hospital of Qingdao University from May 2013 to November 2023.

RESULTS

Among the 103 patients diagnosed with SO, 95 were benign SO (median age: 44.9 years (range, 15-83 years)) and 8 were malignant struma ovarii (MSO) (49.6 years (range, 15-83 years)), malignant cases accounted for 7.8% of the cohort. No statistically significant difference was observed in the median age between patients with benign SO and those with MSO (p = 0.346). Approximately 52.4% of SO patients had an increase in CA125, while CEA, AFP, HE4 and CA199 were basically within the normal range, and these markers had no clinical significance. The ultrasound manifestations were mostly cystic masses or predominantly cystic-solid masses (78/98), and 18 cases were solid masses or predominantly solid-cystic masses. Two patients showed negative results on ultrasound examination and was discovered during another gynecological surgery. Most of the masses are completely separated and multilocular, most with smooth outer margins. Nearly one-half of the masses have punctate or short-line echoes with comet tails, papillary protrusions can be seen on the inner wall of some lesions, and there is usually no blood flow inside the tumor or only a few dotted blood flow signals (79/96). Among the 6 patients with MSO which have ultrasound imaging, 4 patients showed a multilocular cystic mass on ultrasound, with poor sound echo in the cystic part, and 2 patients showed a solid mass on ultrasound with abundant blood flow signals. Immunohistochemistry results showed positive expression rates for thyroid transcription factor-1 (TTF-1) (96%, 24/25), thyroglobulin (TG) (90.5%, 19/21), PAX8 (94.7%, 18/19), and Ki-67 (100% 16/16), though Ki-67 expression levels were generally low, with 15 cases < 5% and 1 case at 50%.

CONCLUSION

Ultrasonographic features-including multilocular cystic-solid masses with septations, hyperechoic "pearl signs," and comet-tail artifacts-may raise suspicion for SO. However, differentiating between benign and malignant cases remains challenging due to significant imaging overlap. A multimodal diagnostic approach incorporating clinical presentation, laboratory findings, and histopathological evaluation is essential for accurate diagnosis and optimal management.