Struma ovarii: MR appearances

A large benign struma ovarii with atypical imaging findings

Struma ovarii is a mature ovarian teratoma characterized by the predominant presence of thyroid-tissue components. Typically, struma ovarii presents as relatively small masses (<10 cm) that often appear as multilocular cystic tumors with solid components. Herein, we report the unique case of a 44-year-old female with a large tumor including a solid mass. The solid components of the tumor comprised typical thyroid tissues with multiple small cystic structures containing colloid-like material. Given the rarity of struma ovarii, atypical imaging features can sometimes be misleading. This article highlights the unusual magnetic resonance imaging characteristics of a large struma ovarii, with a specific focus on the presence of solid components.

Management of malignant struma ovarii: is aggressive therapy justified? Case report and literature review

Background

Struma ovarii (SO) is a rare ovarian teratoma containing predominantly thyroid tissue. In rare situations SO may develop malignancy. Most cases of malignant struma ovarii (MSO) are diagnosed after surgical removal, based on histopathological examination. There are still controversies regarding the extent of surgery and postoperative management in MSO, due to its unpredictable behavior, possible risk of metastasis and relatively high rate of recurrence.

Case Presentation

We present the case of a patient diagnosed with a right ovarian cyst discovered incidentally during routine ultrasound examination. Its rapid growth and pelvic MRI raised the suspicion of a neoplastic process. She underwent total hysterectomy and bilateral adnexectomy. The anatomopathological diagnosis was MSO with follicular variant of papillary thyroid carcinoma. Prophylactic total thyroidectomy was performed, followed by radioactive iodine ablation (RAI), and suppressive therapy with levothyroxine. At 1 year follow-up, the patient was disease free.

Conclusions

Even if latest literature reports consider that completion of local surgery with total thyroidectomy and RAI might be too aggressive in cases of MSO without extraovarian extension, in our case it was decided to follow the protocol for primary thyroid carcinoma, in order to reduce the recurrence risk.

Ovarian teratomas: clinical features, imaging findings and management

Ovarian teratomas are the most common type of germ cell tumors. There are three major subtypes of ovarian teratomas including mature, immature, and monodermal teratomas. Ultrasound, computed tomography and magnetic resonance imaging can demonstrate specific imaging findings for mature teratoma. Imaging features of immature and monodermal teratomas are less specific, but a combination of clinical features and imaging findings can help in the diagnosis. Imaging is also very helpful in guiding management. In this article, we review the epidemiology, histopathology, clinical presentation, imaging features and management of ovarian teratomas.

Struma Ovarii: A Report of Three Cases and Literature Review

Struma ovarii is a variant of mature cystic teratoma, with predominant thyroid element. Confirmatory diagnosis is by histopathology. It may mimic as ovarian malignancy in some. It may be associated with ascites in minority; even CA-125 has been found to be raised in some cases. We here report three cases – two operated for suspected ovarian malignancy in a postmenopausal female and one case operated for persistent benign ovarian cyst with raised CA-125 in a young female. In all histopathological diagnosis was a benign struma ovarii. It is difficult to diagnose these cases preoperatively as there are no specific clinical, radiological or serum markers for these rare tumors in the absence of thyroid biology abnormality. Most cases are diagnosed on histopathology. These benign tumors many times require extensive staging laparotomy for suspected ovarian malignancy in the absence of preoperative diagnosis. Prognosis is good for these tumors. Subtle radiological signs and a clinical suspicion can avoid extensive staging laprotomies in these patients.

Imaging features of complex solid and multicystic ovarian lesions: proposed algorithm for differential diagnosis

Complex solid and multicystic ovarian lesions are broad-spectrum diseases, ranging from benign to malignant. This article describes the broad-spectrum and imaging features of complex solid and multicystic ovarian lesions and illustrates an algorithmic approach to such lesions, focusing on the ultrasonography and magnetic resonance imaging features that allow one to hone the differential diagnosis. Multimodality imaging workup plays an important role in the characterization and differential diagnosis of these diseases. Also, knowledge of the clinical setting and imaging features for the spectrum of complex solid and multicystic ovarian lesions can lead to appropriate management.

Struma ovarii: role of imaging?

As clinical features in struma ovarii patients in the absence of thyrotoxicosis are generally non-specific and resemble ovarian malignancy, preoperative radiological diagnosis becomes all the more relevant in order to avoid ovarian cancer type surgery (including bilateral salpingo-oophorectomy, hysterectomy, omentectomy and occasionally appendectomy) for this usually benign and rare ovarian mass. As struma ovarii is an uncommon entity, it is all the more important to perform state-of-the-art magnetic resonance (MR) imaging, including high-resolution imaging and diffusion-weighted imaging. The goal of this review paper is to give an update of the key findings of both benign and malignant struma ovarii and to present an unusual case of a purely cystic ovarian struma. Key Points • Clinical features in struma ovarii are generally non-specific and resemble ovarian malignancy.• Pre-operative radiological diagnosis is important to avoid ovarian cancer type surgery (bilateral salpingo-oophorectomy, hysterectomy, omentectomy and occasionally appendectomy).• State-of-the-art MR imaging might help to characterise this unusual ovarian mass.• Struma ovarii can occasionally present as a purely cystic lesion.• However, the role of imaging to identify struma ovarii preoperatively remains limited.

Diversity in size and signal intensity in multilocular cystic ovarian masses: new parameters for distinguishing metastatic from primary mucinous ovarian neoplasms

PURPOSE

To differentiate primary mucinous ovarian neoplasms from metastatic ones with MR using diversity in size and signal intensity of multilocular cystic masses.

MATERIALS AND METHODS

Twenty-eight cases of primary malignant or borderline mucinous malignant neoplasms and 14 metastatic ovarian tumors were retrospectively reviewed. We analyzed whether the tumor was unilateral or bilateral, the diversity in the size and signal intensity of each loculus in multilocular tumors, namely the size ratio of the smallest/largest loculus (size diversity ratio), and the standard deviation of the signal intensity at the level with the most varying signal on T2-weighted images within tumors (signal diversity ratio). We performed statistical analysis using the Mann-Whitney U-test.

RESULTS

Bilateral tumors were more commonly observed among metastatic tumors than primary mucinous tumors (2/28 in primary versus 11/14 in metastatic, P < 0.01). The size diversity ratio was higher in primary mucinous tumors than in metastatic tumors (mean, 50.2 versus 23.2; P < 0.01). The signal diversity ratio was also higher in primary mucinous tumors than in metastatic tumors (334.3 versus 231.2; P < 0.01).

CONCLUSION

Bilateral tumors were more common among metastatic tumors, which tended to be composed of cysts of uniform sizes and signal intensities compared with those of primary mucinous tumors.

Imaging of ovarian teratomas: appearances and complications

Ovarian teratomas are the most common germ cell neoplasm. Subtypes of teratoma include mature cystic, immature and the monodermal teratomas. The benign cystic teratoma shows typical imaging manifestations and can be complicated by torsion, rupture and uncommonly malignant degeneration. Uncommon subtypes of teratomas include the immature, which is usually malignant at diagnosis. The growing teratoma syndrome is an uncommon complication reported in patients treated for immature teratomas. The monodermal teratomas which include the struma ovarii may also have specific imaging characteristics that should be recognised on imaging. This paper aims to provide a comprehensive review describing the spectrum of imaging findings of these ovarian tumours and associated complications.

Struma ovarii: CT findings

BACKGROUND

The purpose of this study was to evaluate computed tomographic findings of struma ovarii.

METHODS

Computed tomography (CT) scans of 13 pathologically proven struma ovarii were retrospectively reviewed by two radiologists in consensus. Scans were evaluated for the laterality, size, mass configuration, margins, internal architecture, presence of intracystic high attenuation lesions on precontrast scans, and cyst wall enhancement.

RESULTS

The mean size of the tumors was 11.4 cm (range 4.7-21.0 cm). Mainly cystic (n = 8, 61.5%) or cystic (n = 5, 38.5%) appearance was common to all the tumors. All tumors were unilateral and had smooth margins. The most common internal architecture in the tumors was multicystic architecture (n = 11, 84.6%). Eleven tumors (84.6%) showed a high attenuation lesion in the cyst portion of the mass on precontrast scans and the attenuation ranged from 92.2 to 120.5 Hounsfield units (HU) (mean, 106.8 +/- 8.8 HU). The cyst wall showed no (n = 7, 53.8%), moderate (n = 5, 38.5%), or marked (n = 1, 7.7%) enhancement after administration of contrast medium.

CONCLUSIONS

On CT scans, struma ovarii appeared most often as a smooth marginated multicystic mass with a high attenuation lesion on precontrast scans and no or moderate cyst wall enhancement.

Imaging of gynecological disease (4): clinical and ultrasound characteristics of struma ovarii

OBJECTIVES

To describe the clinical history and ultrasound findings in women with struma ovarii.

METHODS

Women with a histological diagnosis of struma ovarii who had undergone preoperative ultrasound examination were identified from the databases of five ultrasound centers. The tumors were characterized on the basis of ultrasound images, ultrasound reports and research protocols (when applicable) using the terms and definitions of the International Ovarian Tumor Analysis (IOTA) group. In addition, four authors reviewed all ultrasound images and described them using pattern recognition.

RESULTS

Of 31 patients identified, 16 had pure struma ovarii (one malignant), whereas in 15 patients the struma ovarii were 'impure', constituting the major part of a dermoid cyst (all benign, bilateral in one case). Median age was 40 (range, 18-80) years and 22 (71%) patients were of fertile age. Thirteen patients (42%) were asymptomatic, nine (29%) presented with pain, six (19%) with bloating, two (6%) with irregular bleeding and one (3%) with thyreotoxicosis. Most pure struma ovarii (11/16 cases, 69%) contained solid components, but cystic components were always present. The color content at Doppler examination varied from none to abundant. Four patients had ascites. Using pattern recognition the most specific feature of pure struma ovarii was the 'struma pearl', i.e. a smooth roundish solid area, similar, but not identical, to the 'round white ball' seen in dermoid cysts. 'Struma pearls' were present in six cases of pure struma ovarii. Most (10/16, 63%) cases of impure struma ovarii manifested ultrasound features compatible with a dermoid cyst, but six manifested ultrasound features similar to those of pure struma ovarii, 'struma pearls' being seen in three of these.

CONCLUSIONS

The sonographic features of struma ovarii vary. Struma ovarii may be suspected when a 'struma pearl' is seen. Whether 'struma pearls' are indeed a specific ultrasonographic feature of struma ovarii needs to be determined in a prospective study.

Imaging findings of complications and unusual manifestations of ovarian teratomas

Ovarian teratomas can be associated with various complications and demonstrate a wide spectrum of clinical and imaging features. The complications include torsion (16% of ovarian teratomas), rupture (1%-4%), malignant transformation (1%-2%), infection (1%), and autoimmune hemolytic anemia (<1%). These complications require different therapeutic strategies; therefore, timely and accurate diagnosis of these complications is important for optimal patient treatment. In cases of complicated ovarian teratomas, the clinical manifestations provide only limited information and often overlap with those of other diseases. Furthermore, ovarian teratomas may have unusual clinical and imaging manifestations, thereby leading to misdiagnosis. These unusual manifestations include immature teratomas, monodermal teratomas (struma ovarii), combination tumors and collision tumors containing teratomas, and mature cystic teratomas without demonstrable fat or with pure fatty components. To provide adequate treatment and prevent misdiagnosis, it is necessary to be familiar with the imaging findings of both the complications and the unusual manifestations of ovarian teratomas.

A large struma ovarii tumor removed via laparoscopy in a 16-year-old adolescent

Struma ovarii is rare ovarian tumor that is characterized by the presence of at least 50% thyroid tissue on histologic examination. This usually benign neoplasm is predominantly found in women between the ages of 40 and 60 years and infrequently in the pediatric age group. In the foregoing report, we present an unusual case of a large struma ovarii in a 16-year-old adolescent girl with abdominal pain and increasing abdominal girth. Removal of the mass was achieved via a laparoscopic approach. We conclude that the diagnosis of struma ovarii should be considered in adolescent girls presenting with large cystic ovarian masses and that a laparoscopic approach to management is the treatment of choice.

Malignant struma ovarii mimic clear cell carcinoma

INTRODUCTION

Struma ovarii are quite unusual lesions that represent less than 3% of all teratomas and its malignant transformation is very uncommon. The clinical manifestations are characteristic of pelvic tumor and the hormonal metabolism is not usually modified. Radiography, employing ultrasound procedures, is the most commonly used pre-surgical detection method but only histological examination makes the diagnosis. The malignance recognition by pathological study not always is easy; in this sense, it requires an exhaustive sampling of the lesion, being specially carefully in some aspects related with malignant transformation such as extending beyond the capsula and involving peripheral tissues. A thyroidal differentiation must be confirmed by immunohistochemical study and other local processes with similar histology should be ruled out. Given the exceptional character of malignant forms, there does not appear to be unanimous agreement on a standard therapy with a somewhat uncertain prognosis.

CASE REPORT

We show a case of a 22-year-old patient with an ovarian tumor that was discovered by ultrasound examination and surgically removed. The histologic study revealed struma ovarii with malignant transformation towards follicular carcinoma and unlike previously published cases, had a prevalence of clear cells. The patient was submitted to a second surgical staging intervention, with conservative surgery and follow-up controls being considered given that was a young woman with a desire to have children. Laparoscopy was employed as the best method capable to facilitate shorter convalescence.

OUTCOME

Clinical and analytical controls, measuring thyroglobulin levels, has been satisfactory up to the present.

Struma ovarii coexisting with mucinous cystadenoma detected by radioactive iodine

The authors describe a case of struma ovarii coexisting with mucinous cystadenoma. Ultrasonography and magnetic resonance imaging showed a multilocular cystic mass with a solid component. The ovarian tumor demonstrated uptake of I-123 sodium iodide, allowing a preoperative diagnosis of struma ovarii. In women with an unexplained increase in thyroid function and low I-123 uptake in the cervical thyroid gland, scintigraphy of the pelvis should be considered.

Magnetic resonance imaging of the ovary

Magnetic resonance imaging (MRI) of the pelvis can characterize a wide variety of ovarian lesions. We discuss MRI strategies for identification and characterization of ovarian neoplasms and correlate MRI findings with lesion gross pathological and histopathological structure.

Ovarian teratomas: tumor types and imaging characteristics

Ovarian teratomas include mature cystic teratomas (dermoid cysts), immature teratomas, and monodermal teratomas (eg, struma ovarii, carcinoid tumors, neural tumors). Most mature cystic teratomas can be diagnosed at ultrasonography (US) but may have a variety of appearances, characterized by echogenic sebaceous material and calcification. At computed tomography (CT), fat attenuation within a cyst is diagnostic. At magnetic resonance (MR) imaging, the sebaceous component is specifically identified with fat-saturation techniques. The US appearances of immature teratoma are nonspecific, although the tumors are typically heterogeneous, partially solid lesions, usually with scattered calcifications. At CT and MR imaging, immature teratomas characteristically have a large, irregular solid component containing coarse calcifications. Small foci of fat help identify these tumors. The US features of struma ovarii are also nonspecific, but a heterogeneous, predominantly solid mass may be seen. On T1- and T2-weighted images, the cystic spaces demonstrate both high and low signal intensity. Familiarity with the US, CT, and MR imaging features of ovarian teratomas can aid in differentiation and diagnosis.

Cystic struma ovarii: imaging findings

We report three cases of cystic struma ovarii not associated with any solid component. One case was a thin-walled unilocular mass, and the other two cases were multilocular cystic masses. An area of signal void on T2-weighted images and intermediate intensity on T1-weighted images was noted in the two multilocular cases. Preoperative diagnosis was difficult in each case, but struma ovarii should be included in differential diagnoses even in the case of a completely cystic ovarian mass.

MR findings of struma ovarii

This study was performed to characterize MR findings of struma ovarii. In 10 patients, T1- and fast spin echo T2-weighted MR images were obtained in the axial, coronal, and sagittal planes using 1.5 T MR units, and they were retrospectively evaluated for the site, size, components, signal intensity, and contrast enhancement.MR images showed a unilateral complex mass with a multilobulated surface and thickened septa, corresponding pathologically to thyroid follicles and the stroma. Cystic portions had variable signal intensities on T1- and T2-weighted images. The contents of cystic components showing low signal intensities both on T1- and T2-weighted images were viscid gelatinous materials (n=4). Solid portions were relatively well-enhanced. In conclusion, struma ovarii has some characteristic MR appearance of a multilobulated complex mass with thickened septa, multiple cysts of variable signal intensities, and enhancing solid components.

Struma ovarii: MRI findings

We describe the MRI findings in three cases of struma ovarii. In all three cases, MRI showed a multilocular cystic mass with a variable signal intensity within loculi. Some loculi or small cysts within septations showed low signal intensity on T1 weighted images and very low signal intensity on T2 weighted images, corresponding pathologically to gelatinous colloid material in large follicles. In one case, with Gd-DTPA enhanced T1 weighted images, the thick septations and locally thickened wall showed marked enhancement, corresponding microscopically to thyroid tissue.

I-123 uptake in nonfunctional struma ovarii

A case of nonfunctional struma ovarii preoperatively diagnosed by scintigraphy of the pelvis using I-123 NaI is reported. US, CT, and MRI revealed a multilobulated mass composed of cystic and solid components. CT showed cystic components with slightly high density and MRI showed various signal intensities on T1- and T2-weighted images. I-123-scintigraphy of the pelvis showed uptake in the pelvic mass. Microscopic examination revealed the histologic appearance of thyroid tissue accompanied by follicular adenoma. I-123 scintigraphy of the pelvis was useful for reaching the correct preoperative diagnosis in this patient with nonfunctional struma ovarii.