Struma Ovarii

Published on 10/03/2015 by admin

Filed under Obstetrics & Gynecology

Last modified 22/04/2025

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Struma Ovarii

Synonyms/Description

Monodermal, highly specialized mature cystic teratoma comprised of ectopic thyroid tissue

Etiology

Struma ovarii is an extremely rare condition. It is defined as the presence of thyroid tissue comprising greater than 50% of the cellular component in an ovarian tumor, virtually always a teratoma. Struma ovarii is a mature teratoma and accounts for approximately 3% of all ovarian teratomas. It is usually benign, although 5% have malignant components that can occasionally metastasize. Tumors may have features of a multinodular goiter, with colloid nodules and hyperplastic changes. These tumors can vary in size, but most are greater than 5 cm at diagnosis.

Ultrasound Findings

The typical sonographic appearance of struma ovarii is similar to that of a dermoid cyst with one or more echogenic nodules known as struma pearls. Although the echogenic nodules in dermoids have no evidence of color flow on Doppler interrogation, the struma pearl may be quite vascular, which is a valuable clue to the correct diagnosis. Sonographically, most cases of struma ovarii are nonspecific in appearance and are largely solid or have both cystic and solid portions. Less commonly, the tumor is predominantly or entirely cystic, although most of these are multilocular. Occasionally, struma ovarii will have a unilocular cystic appearance, making a specific sonographic diagnosis difficult.
Doppler is very helpful in detecting struma ovarii because most are vascular and demonstrate more blood flow than typically seen in a dermoid cyst.
Up to 17% of patients with benign struma ovarii may have ascites. Struma ovarii may be associated with a contralateral dermoid or other types of teratoma.
There are no specific sonographic features that help distinguish malignant from benign struma ovarii tumors.

Differential Diagnosis

Struma ovarii can mimic a dermoid cyst, although presence of Doppler flow in the solid portions is very helpful to distinguish a struma ovarii from a dermoid. Because struma ovarii can be solid, solid and cystic, or completely cystic with or without septations, the appearance is nonspecific and makes a precise diagnosis almost impossible. Struma ovarii can also masquerade as an endometrioma, other types of teratomas, or essentially any ovarian malignancy, depending on the degree of flow demonstrated by Doppler.

Clinical Aspects and Recommendations

They are most commonly seen in reproductive-age women; however, incidence peaks between the ages of 40 and 60. The possible presence of struma ovarii should be suspected in a woman with hyperthyroidism who has no goiter and minimal thyroid uptake of radioactive iodine. Even among such women, however, true struma ovarii is rare.
Treatment of hyperthyroidism associated with struma ovarii consists primarily of surgical excision, mainly because of the risk of carcinoma. In those patients who are symptomatic or have substantial serologic evidence of hyperthyroidism, use of an antithyroid drug for 4 to 6 weeks before surgery is recommended. The cyst should be removed surgically.

Figures

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Figure S4-1 A, Small echogenic mass whose appearance suggests a dermoid. B, Doppler color flow with moderate vascularity in the mass, a characteristic of struma ovarii.

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Figure S4-2 Struma ovarii presenting as a large, solid, heterogenous mass with several areas of relative increase in echogenicity. Note the presence of blood flow in the mass.

 

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Figure S4-3 A to C, Struma ovarii presenting as a large 8-cm cystic mass with a few septations. The cystic portions have dense, homogeneous echoes and no blood flow. Although the pattern of internal echoes might suggest an endometrioma, the internal echoes are too coarse.

 

Suggested Reading

Coyne C., Nikiforov Y.E. RAS mutation-positive follicular variant of papillary thyroid carcinoma arising in a struma ovarii. Endocr Pathol. 2010;21:144–147.

Doganay M., Gungor T., Cavkaytar S., Sirvan L., Mollamahmutoglu L. Malignant struma ovarii with a focus of papillary thyroid cancer: a case report. Arch Gynecol Obstet. 2008;277:371–373.

Manini C., Magistris A., Puopolo M., Montironi P.L. Cystic struma ovarii: a report of three cases. Pathologica. 2010;102:36–38.

Saba L., Guerriero S., Sulcis R., Virgilio B., Melis G., Mallarini G. Mature and immature ovarian teratomas: CT, US and MR imaging characteristics. Eur J Radiol. 2009;72:454–463.

Zalel Y., Seidman D.S., Oren M., Achiron R., Gotlieb W., Mashiach S., Goldenberg M. Sonographic and clinical characteristics of struma ovarii. J Ultrasound Med. 2000;19:857–861.

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