|Year : 2013 | Volume
| Issue : 1 | Page : 23-25
Hyperthyroidism due to bilateral benign cystic struma ovarii: A rare case report
Bharathi Kannusamy, Anuradha Subramanyam
Department of Pathology, Sri Satya Sai Medical College and Research Institute, Nellikuppam, Tamilnadu, India
|Date of Web Publication||10-Jan-2013|
Department of Pathology, Sri Satya Sai Medical College and Research Institute, Nellikuppam, Tamilnadu
Source of Support: None, Conflict of Interest: None
Struma ovarii is a rare specialized monodermal teratoma of ovary composed predominantly of thyroid tissue (> 50%). Most of the cases are asymptomatic. Hyperthyroidism due to functional struma ovarii is seen only in 5 to 10% of cases. We report here a case of bilateral benign cystic struma ovarii in a 50-year-old lady presenting with signs and symptoms of hyperthyroidism. Her thyroid profile showed elevated levels of total and free thyroxine levels. Pelvic ultrasonogram showed bilateral cystic ovarian tumor along with minimal ascites. 131-I whole body scan revealed bilateral focus of high radioactive iodine uptake in the pelvis. A provisional diagnosis of cystic struma ovarii was made. Abdominal exploration showed cystic mass lesion in both ovaries. She underwent total abdominal hysterectomy with bilateral salphingo-oophorectomy. Histopathological examination confirmed the mass as benign cystic struma ovarii. Signs and symptoms rapidly disappeared after surgical removal of tumor. This rare case is reported here for its unusual clinical presentation.
Keywords: Bilateral struma ovarii, hyperthyroidism, minimal ascites, monodermal teratoma
|How to cite this article:|
Kannusamy B, Subramanyam A. Hyperthyroidism due to bilateral benign cystic struma ovarii: A rare case report. Thyroid Res Pract 2013;10:23-5
|How to cite this URL:|
Kannusamy B, Subramanyam A. Hyperthyroidism due to bilateral benign cystic struma ovarii: A rare case report. Thyroid Res Pract [serial online] 2013 [cited 2018 Jan 16];10:23-5. Available from: http://www.thetrp.net/text.asp?2013/10/1/23/105843
| Introduction|| |
Struma ovarii is a rare ovarian teratoma that consists predominantly of thyroid tissue.  It is usually asymptomatic and unilateral. Bilaterality in struma ovarii is a very rare occurrence constituting only 5 to 8% of cases. We present a rare case of bilateral benign cystic struma ovarii in a post menopausal female with signs and symptoms of hyperthyroidism.
| Case Report|| |
A 50-year-old lady came with 1 year history of palpitation, loss of weight, exophthalmos, and mild abdominal discomfort. Clinically hyperthyroidism was suspected. She had no thyromegaly. Her thyroid profile showed elevated thyroxine levels and decreased thyroid-stimulating hormone (TSH) levels. Laboratory work-up showed the following results.
Thyroid profile: Free T 3 - 6.4 pg/ml, free T 4 - 3.4 ng/dl, TSH - 0.35 U/ml. The values are inductive of hyperthyroidism. Total count - 8500 cells/cu.mm, differential count - P 68% , L 28 % , E 2% , M 2 % . Chest X-ray was normal. Pelvic ultrasonogram revealed cystic mass lesion involving both ovaries and minimal ascites in the peritoneal cavity. Cytologic examination of ascitic fluid showed few lymphocytes and reactive mesothelial cells only. 131-I whole body scan revealed a focus showing high radioactive iodine uptake in the pelvis. Struma ovarii is the provisional diagnosis made by correlating clinical, radiological findings.
Abdominal exploration was planned. Right sided ovarian cystic mass measured 4 × 4 cm and the left sided mass was 3 × 3 cm in size. Uterus, cervix and tubes were normal. She underwent total abdominal hysterectomy with bilateral salphingo oophorectomy. Gross examination of the specimen showed a cystic neoplasm in both ovaries filled with brown gelatinous colloid like material [Figure 1]. Cyst was lined by thin wall without any solid areas or papillary growth. Cysts were examined thoroughly and many bits were taken to rule out malignancy.
|Figure 1: Gross photograph shows bilateral cystic struma ovarii. Cut surface of the neoplasm shows thin walled cyst filled with brownish colloid|
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Microscopic examination of the cyst wall showed only benign thyroid follicles filled with colloid [Figure 2]. No other component of mature teratoma was seen. No atypia was seen in the cells. A thin portion of compressed normal ovarian parenchyma was present in the neoplasm. Hence, it was diagnosed as bilateral benign cystic struma ovarii. Thus, our case was a functional struma ovarii causing signs and symptoms of hyperthyroidism. Functional struma ovarii is very rare accounting for only 5 to 8% of cases. Post-operative period was uneventful. All the signs and symptoms disappeared rapidly after surgical removal of tumor. She became euthyroid after a month of treatment with anti thyroid drugs. Six months of follow-up showed no recurrence.
|Figure 2: Microphotograph shows benign thyroid follicles filled with colloid|
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| Discussion|| |
Struma ovarii is a rare highly specialized monodermal teratoma with the dominant growth of thyroid tissue constituting more than 50% of the tumor. It was first described in 1899. It is commonly seen in the postmenopausal females. Incidence of struma ovarii is about 1 to 4% of all teratomas. Most of the cases are benign, unilateral, asymptomatic and non functional.  Rarely they can be bilateral (6%) and present with thyrotoxicosis, palpable abdominal mass, abdominal discomfort and ascites. Struma ovarii associated with ascites and hydrothorax is known as Pseudo-Meig's syndrome. Size of the tumor ranges from 0.5 cm to 10 cm. Struma ovarii can be seen associated with serous cystadenoma, mucinous cystadenoma, Brenner's tumor and carcinoid tumor.  When struma is admixed with carcinoid tumor as a component it is called as strumal carcinoid. 
Grossly struma is often cystic filled with brown colloid. Microscopically, struma resembles the normal thyroid tissue composed of thyroid follicles filled with colloid. Birefringent crystals of calcium monohydrate can also be present. Struma ovarii may harbor any pathological changes like follicular adenoma, follicular carcinoma, papillary carcinoma and Hashimoto's thyroiditis. ,
Radiologically, struma is seen as a solid and cystic mass. Confirmatory diagnosis is given by pathological examination along with clinical and radiological correlation. Immunohistochemical staining for thyroglobulin may be required to identify the cells as thyroid origin. CA - 125 levels is reported to be elevated in benign struma ovarii. Radio iodide scan is indicated for preoperative diagnosis of functioning struma ovarii presenting with thyrotoxicosis. It will highlight the increased tracer uptake by an active thyroid tissue located in ectopic sites along with low uptake in the cervical thyroid. ,
Very rarely struma is associated with multiple peritoneal implants of varying sizes containing mature thyroid tissue similar to struma. This condition is known as peritoneal strumosis. Peritoneal strumosis is also a benign condition and can present with thyrotoxicosis. 
Malignant struma ovarii is very rare seen only in larger tumors with features of atypia, capsular invasion, metastasis and recurrence.  Only 5 to 10% cases show malignant transformation with papillary carcinoma and follicular carcinoma. Controversies are there in framing the diagnostic pathological criteria for malignant struma ovarii. In recent days, the pathological criteria used to diagnose malignant struma and thyroid carcinomas are very similar and are based on nuclear features and architectural pattern.  Malignant struma has a poor prognosis similar to other malignant ovarian tumors. Thyroid carcinoma metastatic to ovary should be ruled out before diagnosing a malignant struma ovarii.
Surgical resection of the tumor is the treatment of choice for benign struma ovarii. Surgery with adjuvant radio iodine therapy is successful in treating malignant struma and the metastatic functional struma ovarii.
| Conclusion|| |
Functioning struma ovarii is difficult to diagnose and it is one of the differential diagnosis for hyperthyroidism in post menopausal female. Diagnosis of struma ovarii is made easy with the aid of following investigations like thyroid profile, pelvic ultrasonogram and radioiodide scan. Though struma ovarii has a good prognosis, extensive sampling should be done with caution to rule out a nidus of malignancy.
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[Figure 1], [Figure 2]