Struma ovarii

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Aravind Reddy Kothagadi M.B.B.S[2]

Struma ovarii is a variant of dermoid tumors of the ovary in which thyroid tissue components constitute fro more than 50% of the overall tissue. Struma ovarii is comparatively a rare tumor which amounts to 1% of all ovarian tumors and 2.7% of all dermoid tumors. Struma ovarii is a rare monodermal variant of ovarian teratoma. In 1889 by Boettlin. By observing the ovaries discovered the presence of thyroid follicular tissue in Struma ovarii. It is thought that Struma ovarii is mediated by activation of the mitogen activated protein kinase signaling pathway as a critical step in tumorigenesis. Malignant struma ovarii (MSO) are rare tumors which arise from ectopic thyroid tissue in the ovary which is benign. The cause of Struma ovarii has not been identified. Struma ovarii must be differentiated from other diseases like benign and malignant ovarian neoplasm, ovarian cyst, endometrioma and tubo-ovarian abscess. In 2015, the incidence of struma ovarii is approximately 220-240 cases per 100,000 individuals worldwide. Risk factors in the development of Struma ovarii include elevated CA-125 levels, older age, postmenopausal status, and large tumor masses. In cases of metastatic struma ovarii post total thyroidectomy along with radioiodine scanning and radioiodine ablation, the thyroglobulin levels must be monitored as a tumor marker, and diagnostic radioiodine scans should be done to screen for residual or recurrent disease. If left untreated Struma ovarii may lead to thyrotoxicosis. Advanced disease may lead to malignancy, metastases, excessive hormone production and may prove fatal. The most feared complication of struma ovarii is thyrotoxicosis. Other complications include due to metastasis of stroma oavrii. Prognosis is generally excellent under benign conditions and in malignant cases, adjuvant iodine-131 ablation with surgical extirpation has excellent prognosis. The most common presenting symptoms are pelvic pain, abdominal distension followed by abnormal vaginal bleeding. Surgery is the mainstay of treatment for Struma ovarii. For benign cases of struma ovarii the treatment is surgical resection only. For malignant cases of struma ovarii an adjuvant treatment modalities such as radioiodine therapy and external beam radiation are recommended.

Struma ovarii, the tumor was first described in 1889 by Boettlin. By observing the ovaries, he discovered the presence of thyroid follicular tissue in them. Further reports thereafter were published by Gottschalk in 1899.

Malignant Struma ovarii (MSO) are categorized into 3 subtypes namely, Classic variant of papillary thyroid carcinoma (cPTC), Follicular variant of papillary thyroid carcinoma (FVPTC) and Follicular thyroid carcinoma.

It is thought that Struma ovarii is mediated by activation of the mitogen activated protein kinase signaling pathway as a critical step in tumorigenesis. Malignant struma ovarii (MSO) are rare tumors which arise from ectopic thyroid tissue in the ovary which is benign.

The cause of Struma ovarii has not been identified.

Struma ovarii which is potentially malignant should be differentiated from an ovarian mass with cystic, solid, or mixed cystic and solid structure. Struma ovarii must be differentiated from other diseases like benign and malignant ovarian neoplasm, ovarian cyst, endometrioma and tubo-ovarian abscess.

In 2015, the incidence of struma ovarii is approximately 220-240 cases per 100,000 individuals worldwide. Struma ovarii usually occurs in the age groups between 40-60 years. There is no racial predilection to Struma ovarii. Being a tumor of ovarian origin, struma ovarii occurs in females only.

Risk factors in the development of Struma ovarii include elevated CA-125 levels, older age (between 40 – 60 years), postmenopausal status, and large tumor masses.

There is insufficient evidence to recommend routine screening for Struma ovarii. However, in cases of metastatic struma ovarii post total thyroidectomy along with radioiodine scanning and radioiodine ablation, the thyroglobulin levels must be monitored as a tumor marker, and diagnostic radioiodine scans should be done to screen for residual or recurrent disease.

If left untreated Struma ovarii may lead to thyrotoxicosis. Advanced disease may lead to malignancy, metastases, excessive hormone production and may prove fatal. The most feared complication of struma ovarii is thyrotoxicosis. Other complications include due to metastasis of struma oavrii. Prognosis is generally excellent under benign conditions and in malignant cases, adjuvant iodine-131 ablation with surgical extirpation has excellent prognosis. In adults with differentiated thyroid cancer who are treated with high doses of radioiodine seem to have an excellent long-term prognosis.

The most common presenting symptoms are pelvic pain, abdominal distension followed by abnormal vaginal bleeding. Other symptoms such as anepithymia, dyschesia, nausea, fever, intestinal obstruction, frequent micturition and ascites may also be seen.

Patients with Struma ovarii usually appear normal. Physical examination of patients with Struma ovarii is usually remarkable for palpable lower abdominal mass. Pelvic pressure related to a pelvic mass is observed. Struma ovarii appears to occur more frequently in the right adnexa. In some cases ascites may be observed.

Laboratory findings consistent with the diagnosis of Struma ovarii include histopathologic studies and elevated CA-125 levels.

There are no ECG findings associated with Struma ovarii.

There are no x-ray findings associated with Struma ovarii. However, an x-ray may be helpful in the diagnosis of complications of Struma ovarii, such as pleural effusion.

CT scan of the pelvis may be helpful in identifying a mass in the pelvic cavity but may not hold much value in the diagnosis of Struma ovarii. However, a CT scan may be helpful in the diagnosis of complications of Struma ovarii.

MRI may be helpful in the diagnosis of Struma ovarii. Findings on MRI suggestive of Struma ovarii include solid and cystic lesions.

Ultrasound may be helpful in the diagnosis of Struma ovarii. Findings on an ultrasound are suggestive of Struma ovarii occurred more frequently (68.8%) in the right adnexa and was seen with a normal CA-125 level.

Scintigraphy may be helpful in the confirmation of diagnosis of Struma ovarii.

There are no other diagnostic studies associated with Struma ovarii.

The mainstay of treatment for Struma ovarii is surgical therapy. Chemotherapy doesn’t seem to have role in the regular management of papillary and follicular thyroid cancer. It is reserved for patients with progressive disease which is usually not controlled by surgery, I-131, or other treatment modalities. Adjuvant treatment modalities such as radioiodine therapy and external beam radiation are recommended.

Surgery is the mainstay of treatment for Struma ovarii. For benign cases of struma ovarii the treatment is surgical resection only. For malignant cases of struma ovarii an adjuvant treatment modalities such as radioiodine therapy and external beam radiation are recommended.

There are no established measures for the primary prevention of Struma ovarii.

There are no established measures for the secondary prevention of Struma ovarii.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Aravind Reddy Kothagadi M.B.B.S[2]

In 1889, Boettlin was the first who described struma ovarii as an ovarian tumor. By observing the ovaries, he discovered the presence of thyroid follicular tissue in them. Further reports thereafter were published by Gottschalk in 1899.

• In 1889, Boettlin discovered ovarian tumor with the presence of thyroid follicular tissue in the ovary. ^[1]
• In 1895, Von Klden and Gottschalk in 1899 described Struma ovarii as the most common type of monodermal teratoma. ^[2]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Aravind Reddy Kothagadi M.B.B.S[2]

Struma ovarii may be classified in to two subtypes, benign type and malignant type. Malignant Struma ovarii (MSO) are classified into three subtypes; classic variant of papillary thyroid carcinoma (cPTC), follicular variant of papillary thyroid carcinoma (FVPTC) and Follicular thyroid carcinoma.

Struma ovarii may be classified in to two subtypes: benign and malignant.

According to the classification proposed by the World Health Organization (WHO) in 2004 for thyroid carcinomas, malignant struma ovarii (MSO) is classified into three subtypes: ^[1]

• Classic variant of papillary thyroid carcinoma (PTC)
• Follicular variant of papillary thyroid carcinoma
• Follicular thyroid carcinoma

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Aravind Reddy Kothagadi M.B.B.S[2]

It is thought that struma ovarii is mediated by activation of the mitogen activated protein kinase signaling pathway as a critical step in tumorigenesis. Malignant struma ovarii (MSO) are rare tumors which arise from ectopic thyroid tissue in the ovary which is benign. The genes involved in the pathogenesis of malignant struma ovarii include BRAF (35% to 69%), RAS (10%), and RET (5% to 30%). On gross pathological examination, struma ovarii may be present as: Solid and cystic tumor, tumor with several nodules partially separated by gray whitish fibrous tissue, nodules appear tan-brown in color with small dark red areas, Cystic spaces filled with yellow-brown or straw-colored fluid, and focal areas of calcification. Microscopic pathology of struma ovarii is similar to the thyroid tissue with cellular solid or cystic cluster of variable size with cuboidal or columnar morphology and eosinophilic cytoplasm, round nuclei with finely granular chromatin, and Colloid presentation.

• Struma ovarii is a type of monodermal highly specialized ovarian teratomas, consist of mature thyroid tissue.
• It is thought that struma ovarii is mediated by activation of the mitogen activated protein kinase signaling pathway as a critical step in tumorigenesis. This process has been understood by molecular analysis of follicular cell derived thyroid carcinomas. ^[1]
• Malignant struma ovarii (MSO) are rare tumors which arise from ectopic benign thyroid tissue in the ovary. Malignant transformation of struma ovarii is not common and occurs in less than 5% of all cases, and it is even rarer to lead to metastatic disease (5–6%). ^{[2] [3]}
• In malignant struma ovarii (MSO), the cancer can spread to the contralateral ovary; also other sites such as abdominopelvic lymph nodes, the peritoneal cavity, lungs, scalp, brain, diaphragm, and liver may be involved. ^[4]
• Routes of metastasis are: ^{[5] [6] [7]}

• 1) Regional lymphatics to pelvic and paraaortic lymph nodes
• 2) Direct spread to the omentum, peritoneal cavity and the contralateral ovary
• 3) Hematologic dissemination to the bone, lung, liver and brain

• Malignant struma ovarii manifest as follicular carcinoma (causing peritoneal strumosis as a result of peritoneal spread), papillary carcinoma or follicular micro-carcinoma, a variant of papillary carcinoma (showing BRAF and RAS mutations) and rarely with carcinoid and along with lymphoma. ^{[8] [9]}

• The genes involved in the pathogenesis of malignant struma ovarii include BRAF (35% to 69%), RAS (10%), and RET (5% to 30%). ^[1]
• The development of malignant struma ovarii (MSO) along with papillary thyroid carcinomas (PTC) features is associated with mutations in the BRAF of the type which is commonly observed in PTC, therefore it suggests a common pathogenesis for all PTCs regardless of their location. On the contrary, mutations in the RET/RAS/RAF pathway are not observed in BSO (Benign Struma ovarii). ^[1]

The most important extra-ovaries associated conditions with stroma ovarri include:

• Adenomatous or colloid cervical goiters ^[10]
• Hyperthyroidism in postmenopausal woman ^[11]
• Pseudo-Meig’s syndrome ^[12]
• Hashimoto’s thyroiditis ^[13]
• Thyrotoxicosis ^[13]
• Peritoneal strumosis which are benign lesions^[14]

Struma ovarii can be seen associated with other ovarian diseases include: ^[15]

• Ovarian mature cystic teratoma
• Ovarian serous cystadenoma
• Ovarian mucinous cystadenoma
• Brenner’s tumor of ovary
• Carcinoid tumor

On gross pathological examination, struma ovarii may be present as: ^{[16] [17]}

• Solid and cystic tumor
• Tumor with several nodules partially separated by gray whitish fibrous tissue
• Nodules appear tan-brown in color with small dark red areas
• Cystic spaces filled with yellow-brown or straw-colored fluid
• Focal areas of calcification

Microscopic pathology of struma ovarii is similar to the thyroid tissue:

• Cellular solid or cystic cluster of variable size with cuboidal or columnar morphology and eosinophilic cytoplasm
• Round nuclei with finely granular chromatin
• Colloid is seen

May develop pathologies seen in the thyroid gland; for instance papillary thyroid carcinoma in a struma ovarii can be recognized in hematoxylin and eosin-stained tissue with branching papillae with atypical malignant cytologic features including nuclear groves, overlapping, and enlargement. ^[18]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:

The cause of Struma ovarii has not been identified. To review risk factors for the development of Struma ovarii, click here.

The cause of Struma ovarii has not been identified. To review risk factors for the development of Struma ovarii, click here.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Aravind Reddy Kothagadi M.B.B.S[2]

Struma ovarii is a potentially malignant tumor, that should be differentiated from an ovarian mass with cystic, solid, or mixed cystic and solid structure. Struma ovarii must be differentiated from other diseases like benign and malignant ovarian neoplasm, ovarian cyst, endometrioma and tubo-ovarian abscess.

• Struma ovarii is a potentially malignant tumor, that should be differentiated from an ovarian mass with cystic, solid, or mixed cystic and solid structure such as: ^{[1][2][3][4][5][6][7] [8][9]}

• Various benign and malignant ovarian neoplasms
• Endometrioma
• Ectopic Pregnancy
• Metastatic thyroid cancer to the ovary
• Ovarian cyst(Physiological)
• Tubo-ovarian abscess
• Hydrosalpinx
• Hyperthyroidism

Cause of thyrotoxicosis	TSH receptor antibodies	Thyroid US	Color flow Doppler	Radioactive iodine uptake/Scan	Other features
Struma ovarii	–	Variable	Reduced/absent flow	↓	Abdominal RAIU
Toxic nodular goiter	–	Multiple nodules	–	Hot nodules at thyroid scan	–
Graves’ disease	+	Hypoechoic pattern	↑	↑	Ophthalmopathy, dermopathy, acropachy
Toxic adenoma	–	Single nodule	–	Hot nodule	–
Subacute thyroiditis	–	Heterogeneous hypoechoic areas	Reduced/absent flow	↓	Neck pain, fever, and elevated inflammatory index
Painless thyroiditis	–	Hypoechoic pattern	Reduced/absent flow	↓	–
Amiodarone induced thyroiditis-Type 1	–	Diffuse or nodular goiter	↓/Normal/↑	↓ but higher than in Type 2	High urinary iodine
Amiodarone induced thyroiditis-Type 2	–	Normal	Absent	↓/absent	High urinary iodine
Central hyperthyroidism	–	Diffuse or nodular goiter	Normal/↑	↑	Inappropriately normal or high TSH
Trophoblastic disease	–	Diffuse or nodular goiter	Normal/↑	↑	–
Factitious thyrotoxicosis	–	Variable	Reduced/absent flow	↓	↓ Serum thyroglobulin

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Aravind Reddy Kothagadi M.B.B.S[2]

In 2015, the incidence of struma ovarii is approximately 220-240 cases per 100,000 individuals worldwide. Struma ovarii usually occurs in the age groups between 40-60 years. There is no racial predilection to Struma ovarii. Being a tumor of ovarian origin, struma ovarii occurs in females only.

• In 2015, the incidence of struma ovarii is approximately 220-240 cases per 100,000 individuals worldwide.

• Struma ovarii commonly affect middle aged women between 40-60 years old. ^[1]
• In rare cases, Struma ovarii occur before puberty.

• There is no racial predilection for Struma ovarii.

• As stuma ovarri is an ovarian cancer, it only occur in women, and men are not affected.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Aravind Reddy Kothagadi M.B.B.S[2]

Risk factors in the development of malignant struma ovarii from benign type include elevated CA-125 levels, older age, postmenopausal status, and large tumor masses.

• The most potent risk factors in the development of malignant struma ovarii from benign type are: ^[1]

• Elevated CA-125 levels
• Older age (between 40 – 60 years)
• Large tumor masses
• Postmenopausal status

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Aravind Reddy Kothagadi M.B.B.S[2]

There is insufficient evidence to recommend routine screening for Struma ovarii. However, in cases of metastatic struma ovarii post total thyroidectomy along with radioiodine scanning and radioiodine ablation, the thyroglobulin levels must be monitored as a tumor marker, and diagnostic radioiodine scans should be done to screen for residual or recurrent disease.

• There is insufficient evidence to recommend routine screening for Struma ovarii.
• For follow-up as a marker of recurrence, serum thyroglobulin levels and I-131 scan may be used. ^{[1] [2] [3]}
• The I-131 scan or thyroglobulin have no aid in the follow-up if thyroidectomy is not performed. ^[4]
• In cases of metastatic struma ovarii post total thyroidectomy along with radioiodine scanning and radioiodine ablation, the thyroglobulin levels must be monitored as a tumor marker, and diagnostic radioiodine scans should be done to screen for residual or recurrent disease. ^[5]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:

If left untreated Struma ovarii may lead to thyrotoxicosis. Advanced disease may lead to malignancy, metastases, excessive hormone production and may prove fatal. The most feared complication of struma ovarii is thyrotoxicosis. Other complications include due to metastasis of struma oavrii. Prognosis is generally excellent under benign conditions and in malignant cases, adjuvant iodine-131 ablation with surgical extirpation has excellent prognosis. In adults with differentiated thyroid cancer who are treated with high doses of radioiodine seem to have an excellent long-term prognosis.

• If left untreated struma ovarii may lead to thyrotoxicosis. ^[1]
• Advanced disease may lead to malignancy, metastases, excessive hormone production and may be fatal. ^[2]

• One of struma ovarii complications is thyrotoxicosis. Other complication is metastasis of stroma ovarii in malignant types.^[3]

• Prognosis is generally excellent in benign conditions. In malignant cases, adjuvant iodine-131 ablation with surgical excision has very good prognosis.
• The 5, 10 and 20-years survival rate of patients with struma ovarii is approximately 96.7%, 94.3%, and 84.9%, respectively. ^[4]
• In adults with differentiated thyroid cancer who are treated with high doses of radioiodine seem to have an excellent long-term prognosis. ^[5]

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