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Year : 2019  |  Volume : 12  |  Issue : 6  |  Page : 516-520  

Uncommon tumor with rare variant: Cystic struma ovarii – A case report with review of literature

Department of Pathology, LLRM Medical College, Meerut, Uttar Pradesh, India

Date of Submission04-Oct-2018
Date of Acceptance18-Feb-2019
Date of Web Publication17-Oct-2019

Correspondence Address:
Veer Karuna
Department of Pathology, LLRM Medical College, Meerut, Uttar Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/mjdrdypu.mjdrdypu_182_18

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Struma ovarii is a very unusual and rare type of monodermal teratoma presenting as a solid pelvic mass. Struma ovarii concurrently occurring with cystic variant is rarely reported. To the best of our knowledge, only 4–5 cases of cystic struma ovarii have been reported in the past two decades. In exceptionally rare cases, it can be malignant. We present an ovarian teratoma which was grossly partially solid and partially cystic filled with mucoid content, causing the diagnosis of struma ovarii to be unnoted. There may be the source of many diagnostic problems if the microscopic examination showed flattened cystic wall with entrapped minimal thyroid follicles in counterpoint to struma ovarii resulting in confusion with other cystic ovarian tumors. No other component of mature teratoma was found in the present case. Presence of a few thyroid follicles and flattened epithelial lining needs extensive sampling and immunohistochemical staining for thyroglobulin and thyroid transcription factor-1 to establish an exact diagnosis. The aim of this literature is to delimitate cystic struma ovarii rarity and for the diagnostic dispute encountered.

Keywords: Cystic, monodermal teratoma, ovary, thyroid tissue

How to cite this article:
Karuna V, Gupta P, Verma N, Saroj AK. Uncommon tumor with rare variant: Cystic struma ovarii – A case report with review of literature. Med J DY Patil Vidyapeeth 2019;12:516-20

How to cite this URL:
Karuna V, Gupta P, Verma N, Saroj AK. Uncommon tumor with rare variant: Cystic struma ovarii – A case report with review of literature. Med J DY Patil Vidyapeeth [serial online] 2019 [cited 2022 Jul 2];12:516-20. Available from: https://www.mjdrdypv.org/text.asp?2019/12/6/516/269418

  Introduction Top

In 1889, Boettlin first described the highly specialized and rare tumor entitled as struma ovarii that represents >50% major cellular component of thyroid tissue in the ovary. In 1933, Plaut confirmed that follicular cells of struma ovarii are morphologically and biochemically identical to the cells present in thyroid tissue. Struma ovarii is accounting <4% of all ovarian teratoma and 0.3% of all ovarian tumors.[1],[2] Common age of presentation is between 40 and 60 years, usually unilateral, but cases have been reported in older postmenopausal women and uncommonly occurrence in prepubertal girls is also noted. Clinical complaints including abdominal mass, pain and less common are ascites and hyperthyroidism of this tumor are similar to the other ovarian tumors.[3],[4] Struma ovarii exists as several variants; it can be cystic or solid type. Cystic type is a rare, distinctive variant and can lead to errors in diagnosis due to the presence of minimal quantity of thyroid tissue, thus resulting in confusion with other cystic ovarian tumors. Most of the cases are multilocular cysts, but about 10% are unilocular.[5] The vast majority of struma ovarii are benign, and malignant transformation is very uncommon and found in a small percentage of cases with metastasis in 10% cases. Most common malignancy is papillary carcinoma followed by follicular type.[2],[6] In the World Health Organization, 2010, struma ovarii and malignant thyroid tumors arising within struma are included in the thyroid tumor group under the heading monodermal teratomas and somatic-type tumors arising from dermoid cysts.[7],[8] Ultrasound, computed tomography (CT), or magnetic resonance imaging (MRI) has minor important role for diagnosis as they shows only adnexal mass exhibiting few solid and cystic areas, whereas scintigraphy with radioiodine (131 I) which shows active thyroid tissue in the pelvis, but to confirm the diagnosis, histologic examination and immunocytochemistry are necessary. Treatment is laparotomy.[4] Here, we present a rare case of cystic struma ovarii in a unilateral ovary, diagnostic difficulty.

  Case Report Top

A 38-years old female, para four patient, after taken proper consent, admitted to the Department of Obstetrics and Gynecology with the chief complaints of pain and swelling in the right lower quadrant of the abdomen for 2 years. History of amenorrhea of 1 year was present. On physical examination, the swelling was tender. CT scan was done in the past, but reports of which were not available. Routine complete blood count, serum biochemistry, and thyroid hormones assay (T3, T4, and thyroid-stimulating hormone [TSH]) were within normal limits. No signs of ascites or hyperthyroidism were noted. Gynecological and family history was unremarkable. A proper concent was taken and total abdominal hysterectomy with bilateral salpingo-oophorectomy was performed, and the specimen was sent to the department of pathology in a well-labeled container filled with 10% formalin. Gross examination revealed uterus with cervix measuring 8 cm × 4 cm × 3 cm. Bilateral  Fallopian tube More Detailss and left-sided ovary were unremarkable. Right-sided ovary which was enlarged had smooth white, lobulated outer surface, and measured 6.5 cm × 5 cm × 3 cm, and on sectioning, it showed cystic areas filled with tan to greenish brown gelatinous material resembling colloid-filled thyroid tissue intermingled with solid areas [Figure 1]. No areas of papillary projections, hairs, bone, or cartilage were seen. Multiple sections taken from the uterus, cervix, bilateral fallopian tubes, and ovaries were embedded in paraffin and stained with hematoxylin and eosin were studied. On histology, myometrium showed adenomyosis. Bilateral tubes and left ovary showed unremarkable histology. Sections from the multiloculated right ovarian cystic mass showed a cyst wall; there was a small number of thyroid follicles filled with colloid. Some follicles were cystically dilated. Sections from other areas showed a cyst wall of fibrocollagenous tissue lined by nonspecific appearing flat to low cuboidal epithelium [Figure 2]. Aggregates of numerous foamy macrophages and calcification were also noted in the wall lining. Specimen was adequately sampled, but no other teratomatous elements or malignant tissue was recognized. Immunohistochemical staining revealed thyroglobulin positivity [Figure 3]. The final diagnosis of struma ovarii, cystic type, was made.
Figure 1: Cut section of ovarian cystic mass showing multiloculations with inspissated mucoid material

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Figure 2: Collection of thyroid tissue within the thickened cystic wall, filled with colloid, and lined by benign follicular epithelium

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Figure 3: Thyroid follicles showed thyroglobulin positivity

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Discussion and review of literature

Struma ovarii is a benign, monodermal ovarian teratoma, which was initially described by Bottlin in 1889 after that Pick in 1902 and 1903 recognized that struma ovarii was composed of thyroid tissue. In 1956, Wetteland described the malignant struma ovarii.[9] About 1%–2% of teratomas showed struma ovarii which was composed of >50% of thyroid tissue, thus the name struma ovarii. The extremly rare cystic variety of struma ovarii is Xcharacterized by a prominent cystic confi guration with a paucity of thyroid tissue component and covering of nonspecific flat or cuboidal epithelium that misleads the diagnosis. Presence of thyroid tissue were also found in 15% cases ovarian teratomas.[10],[11]

Cystic variant of struma ovarii is a very rare lesion. On extensive search, <6 cases of cystic struma ovarii have been reported in the literature so far. It is histologically different from other dermoid cysts as it does not contain other teratoma components. Struma ovarii pose a diagnostic dilemma, especially when they have cystic configuration.[5]

Struma ovarii can occur at any age, even in children, but the average age of onset is fifth decade. In the present study, the age of presentation of the patient is 38 years. After review of the literature, we found that most of the cases were seen in the age group of 30–45 years.[10],[12],[13],[14] Incidence of struma ovarii reported in young age was found in some studies. Manini et al. did study in three cases of cystic struma ovarii aged 16, 20, and 40 years, respectively. In a report of Szyfelbein et al., women aged 23–83 years are described in 20 cases. Ameer et al. described a case of 25 years women.[15],[16],[17],[18] Case report regarding malignant struma ovarii in young female patients was also reported in the study of Mani et al. and Saima et al.[19],[20]

Struma ovarii are usually asymptomatic, diagnosed incidentally after surgery for pelvic mass.[21] Common clinical presentations include pelvic mass, abdominal pain, and menstrual irregularities, and unusual presentations are hyperthyroidism, ascites, and deep vein thrombosis. The combination with markedly elevated CA-125 is a rare clinical entity that indicates the malignant transformation. Previous reports have shown that up to 47.1% of cases are without symptoms or are accompanied by nonspecific symptoms that are similar to other ovarian tumors. In our case report, the chief symptoms were abdominal pain and amenorrhea.[9],[22],[23]

In 1934, Salmon described the relation of pleural effusion with benign pelvic tumors. In 1937, Meigs and Cass described seven cases of ovarian fibromas associated with ascites and pleural effusion. Meigs' syndrome is defind as triad of benign ovarian tumor, pleural effusion and ascitis. If this clinical manifestations presented in other pelvic organ was termed as Pseudo-Meigs.[24],[25],[26] Kortekaas and Pelikan in their results emphasize that the clinical presentation of an ovarian mass might be ovarian cancer but can masquerade as something uncommon like Meigs' syndrome.[27] Nagakura et al. studied a case of metastatic ovarian carcinoma associated with Pseudo-Meigs' syndrome.[28]

The association of Pseudo-Meigs' syndrome and elevation of CA-125 to the struma ovarii is a rare condition that can lead misdiagnosis of ovarian cancer. In the study of Fujiwara et al., CA-125 level was raised with Meigs' syndrome which was ruled out based on increased uptake of131 I.[29] Bokhari et al. in their study concluded that ovarian mass with elevated CA-125 can mimic carcinoma clinically which was confirmed as multicystic struma ovarii on histology.[30]

Approximately, 0.8%–3% of struma ovarii have functional thyroid tissue, with major proportion being nonfunctional. About 5%–15% reveal hyperthyroidism representing the functioning thyroid tissue in the ovary that resolves after complete resection.[17],[31] Ali, Aida, Bharathi, and Anuradha documented variability in serum values of thyroid function test in women presented with an ovarian mass. Hormonal findings revealed increased thyroid function, but the thyroid gland appeared normal in size and texture. Reason for raised thyroid hormone in struma ovarii may be different mechanism from classic thyroid hyperthyroidism.[31],[32] It is postulated that struma ovarii is an autonomous hormone-secreting tumor or that the ovarian thyroid tissue is stimulated by TSH receptor antibody.[9] In our case, there were no hyperthyroid symptoms because of normal thyroid profile.

Ultrasonography (USG), CT, and MRI have been widely used to investigate the ovarian mass, but definite diagnosis of struma ovarii through this investigation is difficult with nonspecific findings. Ikeuchi et al. introduced the role of MRI and CT findings in cystic lesion of struma ovarii.[30] On CT scan, intracystic lesion of ovarii is highly attenuated on precontrast scans and no or moderate cyst wall enhancement indicates the presence of viscid gelatinous colloid material, but on MRI, the cystic parts can demonstrate both high- and low-signal intensities on T1- and T2-weighted images, which depend on the viscosity of the fluid.[29],[33] Jong et al. also proposed that cystic portions of struma show variable signal intensities and enhancing solid components.[34] In the present case, we are unable to comment on CT and MRI findings as the reports were missing by subject.

USG has limited role in the diagnosis of struma ovarii, suspecting in about 11.8% of cases only. In the three cases' study of Khediri et al., the difference in USG findings was clearly found; as three cases were compatible respectively with the benign ovarian cyst, heterogeneous echogenicity, and presence of septa, and in the third case, the two ovaries were normal. This finally concluded that preoperative diagnosis of struma ovarii using imaging does not have any characteristic.[23]

In the study of Savelli et al., they compared the USG findings with histology and concluded that solid areas and the “struma pearls” seen on ultrasound examination corresponded to thyroid tissue in the histological specimens. Struma pearls are defined as well-circumscribed rounded areas of solid tissue with a smooth surface.[12] According to a study by Jong et al., to diagnose of struma ovarii, no specific radiologic findings are present.[34]

Thyroid tissue may be a part of mature cystic teratoma (dermoid cyst). Association of struma ovarii with serous or mucinous cystadenomas, Brenner tumor, carcinoid tumor, and dermoid cyst has been reported in some literature. In a case report of Hemalatha et al., the initial diagnosis of struma ovarii was made in spite minimal thyroid tissue, but supportive features of gross and resections revealed mucinous lining wall made the final diagnosis of cystic struma ovarii with mucinous adenoma. In a study of Swati et al., the final diagnosis of struma ovarii with serous cystadenoma in a background of tubercular oophoritis was rendered.[5],[35],[36] Association of struma ovarii with torsion was also reported in a study by Goubaa et al.[37]

Despite its name, struma ovarii is not restricted to the ovary. Cases of struma salpingii struma uteri attached to the uterine cervix and vaginal wall and struma testis with malignant transformation along with metastasis in the lung have also been reported.[38],[39],[40]

In this case report, we have highlighted the importance of various imaging techniques, clinical presentation, and chances the malignant transformation in struma ovarii along with the role of gold standard histopathology technique in the diagnosis of cystic struma ovarii with minimal thyroid tissue.

To conclude, struma ovarii is typically identified as a brown or green-brown solid, gelatinous mass. It is frequently associated with mature cystic teratoma or rarely with serous and mucinous adenoma. Most of the struma ovarii are solid or solid and cystic on macroscopic examination and predominantly or entirely cystic tumors and can lead to errors in diagnosis. Most of the latter cases are multilocular cysts. The epithelial lining of the cysts can have a largely nonspecific appearance composed of flattened to cuboidal cells. Clues to the correct diagnosis include the identification of thyroid follicles in the cyst wall or in fibrous septa separating locules of tumor and positivity for thyroglobulin and thyroid transcription factor-1. We recommend that cystic struma ovarii should be considered in the differential diagnosis of all ovarian cystic lesions and adequate sampling of the specimen should be done.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.

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  [Figure 1], [Figure 2], [Figure 3]

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