struma ovarii

What is Struma Ovarii?

Struma ovarii is a rare ovarian tumor defined by the presence of thyroid tissue comprising more than 50% of the overall mass [2]. It's a type of monodermal teratoma, also known as dermoid cyst, which is composed entirely or predominantly of mature thyroid tissue [4].

Characteristics

Struma ovarii accounts for less than 1% of all ovarian tumors and 2-4% of all ovarian teratomas [3]. It's a relatively rare condition, representing about 3% of all ovarian teratomas and 0.5% of all ovarian tumours [5]. The tumor is usually benign, but malignant transformation can occur in about 5% of cases [6].

Symptoms

The symptoms of struma ovarii may include abdominal or pelvic pain, a palpable lower abdominal mass, and clinical hyperthyroidism due to the production of thyroid hormones by the tumor tissue [1]. However, most patients are asymptomatic at presentation.

Diagnosis

Struma ovarii is typically diagnosed through imaging studies such as ultrasound and CT scans, which show a unilateral adnexal mass with characteristic features of thyroid tissue [7].

Treatment

Surgical resection of struma ovarii is the primary treatment for this condition, and it can be curative in most cases [11].

Symptoms of Struma Ovarii

Struma ovarii, a rare ovarian tumor, can manifest with various symptoms, which are often similar to those of other ovarian tumors. The symptoms may vary from one individual to another, but most cases are asymptomatic.

• Abdominal pain or swelling: Depending on the volume of the mass, abdominal pain or swelling can be present in some cases [8][11].
• Abnormal vaginal bleeding: Vaginal bleeding, either light or heavy, can occur due to the tumor's presence [10][13].
• Ascites or deep vein thrombosis: In rare instances, ascites (fluid accumulation in the abdomen) or deep vein thrombosis may be present [8][9].
• Elevated thyroid function: In some cases (5-20%), struma ovarii can cause hyperthyroidism or thyreotoxicosis due to functioning ectopic thyroid tissue [11].

Commonly Asymptomatic

Most patients with struma ovarii are asymptomatic, and the presence of an ovarian tumor is often incidentally discovered during a routine examination. In one series, no definite symptoms were present in 14 out of 34 patients [2]. The symptoms can be nonspecific and resemble those of other ovarian tumors.

References

• [1] Struma ovarii is a rare ovarian tumor defined by the presence of thyroid tissue comprising more than 50% of the overall mass.
• [2] Struma ovarii is a specialized or monodermal teratoma predominantly composed of mature thyroid tissue.
• [8] Systemic symptoms may include nausea, vomiting, poor appetite, weight loss, constipation, and urinary frequency.
• [10] Clinical symptoms that may manifest due to the presence of a struma ovarii are lower abdominal pain, palpable lower abdominal mass, abnormal vaginal bleeding, ascites, hydrothorax, elevated thyroid function, and rarely thyroid tumors.
• [11] Which are the symptoms? Most cases of struma ovarii are asymptomatic. Depending on the volume of the mass, abdominal pain, distention, urinary, or bowel dysfunction due to extrinsic compression might be present.
• [13] Struma ovarii, originally described by von Kalden in 1895, occurs more often in countries where goiter is endemic and has maximum incidence in the fifth decade.

Diagnostic Tests for Struma Ovarii

Struma ovarii, a rare ovarian tumor composed of thyroid tissue, can be challenging to diagnose. Various diagnostic tests are used to confirm the presence and extent of this condition.

• Ultrasound: An ovarian cyst with a large solid component on ultrasound may raise suspicions of struma ovarii [2].
• Magnetic Resonance Imaging (MRI): MRI is recommended by Nurliza Binti Md et al. for preoperative diagnosis, along with serum thyroglobulin levels [11].
• Iodine-123 scanning: This test evaluates active thyroid tissue in the pelvis or abdomen and can be used to confirm struma ovarii [10].
• Serum thyroglobulin testing: Elevated levels of serum thyroglobulin may indicate the presence of struma ovarii [11].
• Histological examination: The diagnosis of malignant struma ovarii is usually based on histological features of the resected ovary, as no specific imaging features are available to diagnose malignancy [7].

Additional Diagnostic Tests

Other tests that may be used in conjunction with these diagnostic tests include:

• I-131 scintigraphy: This test can be used to confirm struma ovarii and assess its functional activity [12].
• Computed Tomography (CT) scans: CT scans may be used to evaluate the extent of the tumor and any potential metastasis [13].

Important Considerations

It is essential to note that elevation of CA-125 is not diagnostic of a malignant ovarian tumor and can occur in benign struma ovarii [14]. Rarely, Grave’s disease or a toxic adenoma can coexist with struma ovarii.

References:

[2] - Context 1 [7] - Context 7 [10] - Context 10 [11] - Context 11 [12] - Context 12 [13] - Context 13 [14] - Context 14

Treatment Options for Struma Ovarii

Struma ovarii, a rare ovarian tumor composed predominantly of thyroid tissue, can be treated with a combination of surgical and medical interventions.

• Surgical Resection: The primary treatment for struma ovarii is surgical resection of the tumor. This involves removing the affected ovary and surrounding tissues.
  • [4] states that surgical resection followed by adjuvant radioiodine therapy has been accepted as the definitive therapeutic approach leading prevention of disease metastasis or recurrence.
• Adjuvant Radioiodine Therapy: After surgical resection, adjuvant radioiodine therapy may be recommended to destroy any remaining thyroid tissue and prevent recurrence.
  • [7] mentions that even in malignant cases, adjuvant iodine-131 ablation with surgical extirpation has proven curative.
• Antithyroid Medicines: In some cases, antithyroid medicines can be used to remove thyrotoxic symptoms and signs before surgery. Surgery should be scheduled as soon as possible after medication treatment.
  • [9] suggests that antithyroid medicines can be used to manage thyrotoxic symptoms before surgery.

Additional Treatment Considerations

• Total Thyroidectomy: In cases where the tumor is malignant, a total thyroidectomy may be performed to remove all thyroid tissue.
  • [15] describes a case of a 49-year-old woman who underwent a left ovarian malignant struma ovarii resected followed two months later by a total thyroidectomy.

It's essential to note that the final management and treatment journey of the patient should be determined within an expert multidisciplinary setting, taking into account both the diagnostic findings and the overall patient profile.

Differential Diagnosis of Struma Ovarii

Struma ovarii, a rare ovarian tumor composed predominantly of thyroid tissue, can be challenging to diagnose due to its similarity in appearance and symptoms with other conditions. The differential diagnosis for struma ovarii includes:

• Mature cystic teratoma: A complex cystic mass with fat and calcifications that does not show uptake on thyroid scans.
• Cystadenoma or cystadenocarcinoma: A type of ovarian tumor that can present with similar symptoms to struma ovarii.
• Endometriosis: A condition where tissue similar to the lining of the uterus grows outside the uterus, which can cause abdominal pain and a palpable mass.
• Tubo-ovarian abscess: An infection of the fallopian tube and ovary that can present with similar symptoms to struma ovarii.
• Metastatic tumor: A cancerous tumor that has spread from another part of the body, which can be difficult to distinguish from struma ovarii.

Key Features for Differential Diagnosis

To differentiate struma ovarii from these conditions, the following features are important:

• Imaging studies: CT scans and MRI assessments can help exclude advanced stage or metastatic malignancy.
• Histological examination: A biopsy of the tumor is essential to confirm the diagnosis of struma ovarii.
• Clinical presentation: The presence of clinical hyperthyroidism, lower abdominal pain, and a palpable mass are characteristic symptoms of struma ovarii.

References

[4] Struma ovarii accounts for less than 1% of all ovarian tumors, making it a rare entity. [8]

[10] The clear/oxyphilic cells of struma ovarii can mimic morphology of clear cell ovarian carcinoma, Sertoli cell tumor, and steroid cell tumor.

[14] Mature cystic teratoma typically presents as a complex cystic mass with fat and calcifications, but does not show uptake on thyroid scans.