Malignant struma ovarii

An Extremely Rare Case of Poorly Differentiated Thyroid Carcinoma Arising in Malignant Struma Ovarii and Concurrent Papillary Thyroid Carcinoma: A Case Study

Ovarian tumors can be classified by their origin - epithelial tumors, germ cell tumors, and stromal tumors. Malignant struma ovarii (MSO) are 0.01% of all ovarian tumors. In order to be classified as a struma ovarii, more than 50% of the teratoma consists of thyroid tissue. The thyroid tissue in the struma ovarii exhibits the same histological and physiological properties as that of the cervical thyroid tissue. Poorly differentiated thyroid carcinoma (PDTC) is an extremely rare occurrence when arising from an MSO. Including this case report, there are only 10 reports of PDTC in the setting of MSO. Of these cases, this patient is the only one who presented with concurrent primary thyroid carcinoma (PTC). This case study examines how invaluable intra-professional collaboration is for appropriate diagnosis, along with attention to detail of identifying markers in pathology sections and use of the appropriate immunohistochemical analysis.

Tyrosine kinase inhibitor treatment and long-term follow-up for metastatic malignant struma ovarii

Metastatic malignant struma ovarii (MMSO) is a very rare disease (in the United States, less than one case in 10 million females annually). However, this incidence rate is due to a paucity of data regarding diagnosis, treatment, and follow-up. Herein, we describe the case of a 14-year-old female who presented with MMSO, which later metastasized and was followed up on for over 10 years. The patient underwent right oophorectomy surgery and was then treated with a combination of radioactive iodine followed by iodine scans to detect the absorption of radioiodine in the metastatic sites, and radiation therapy to treat skeletal lesions. She subsequently received treatment with the tyrosine kinase inhibitors (TKIs), sorafenib and then lenvatinib, as treatments for advanced disease, thereby achieving long-term disease stability. This case report, which adds to the limited data available on MMSO treatment, suggests that patients treated with a combination of radioactive iodine, radiation therapy, and TKIs can result in good responses and long-term overall survival.

Malignant struma ovarii with a robust response to radioactive iodine

SUMMARY

Struma ovarii is a rare, usually benign ovarian tumour with malignancy occurring in <5% of cases. Metastases, particularly seeding to bone, are extremely rare. Presentation is variable but often features local pain and/or ascites and hyperthyroidism may occur. It is not established how to best treat and follow patients with extensive disease. Case reports of radioiodine (I131) ablative therapy following thyroidectomy have shown reduced recurrence. We describe the case of a 33-year-old woman who presented with bone pain and was diagnosed with skeletal metastases with features of follicular thyroid carcinoma. However, thyroid pathology was benign. She recalled that 5 years prior, an ovarian teratoma was excised, classified at that time as a dermoid cyst. Retrospective review of this pathology confirmed struma ovarii without obvious malignant features. The patient was found to have widespread metastases to bone and viscera and her thyroglobulin was >3000 µg/L following recombinant TSH administration prior to her first dose of I131. At 25 months following radioiodine treatment, she is in remission with an undetectable thyroglobulin and clear I131 surveillance scans. This case demonstrates an unusual presentation of malignant struma ovarii together with challenges of predicting metastatic disease, and demonstrates a successful radioiodine regimen inducing remission.

LEARNING POINTS

Malignant transformation of struma ovarii (MSO) is extremely rare and even rarer are metastatic deposits in bone and viscera. MSO can be difficult to predict by initial ovarian pathology, analogous to the difficulty in some cases of differentiating between follicular thyroid adenoma and carcinoma. No consensus exists on the management for post operative treatment of MSO; however, in this case, three doses of 6Gbq radioiodine therapy over a short time period eliminated metastases to viscera and bone. Patients should continue to have TSH suppression for ~5 years. Monitoring thyroglobulin levels can predict recurrence.

Extensive peritoneal implant metastases of malignant struma ovarii treated by thyroidectomy and 131I therapy: A case report

RATIONALE

Malignant struma ovarii is extremely rare in the clinic. The diagnosis and modalities of treatment are still controversial. Here we describe a case of extensive peritoneal implant metastasis originating from malignant struma ovarii discovered 14 years after ovariectomy and chemotherapy.

PATIENT CONCERNS

A 48-year-old female was admitted to our clinic due to hematochezia with a past history of left malignant struma ovarii. Enhanced computed tomography (CT) examination suggested multiple metastasis nodules in the abdomen and pelvic cavity.

DIAGNOSES

Laparoscopy biopsy results of intraperitoneal nodules showed a metastasis of papillary thyroid carcinoma. While pathological examination after total thyroidectomy showed no definite malignant tumor component in the thyroid tissue. Finally, combined with the patient's past history of malignant struma ovarii, peritoneal implantation metastasis derived from the malignant struma ovarii was diagnosed.

INTERVENTIONS

The patient was treated by total thyroidectomy and iodine 131 (I) therapy. Post-therapy iodine scan and the single-photon emission computed tomography/computed tomography (SPECT/CT) fusion image showed iodine uptake in the distal descending colon, sigmoid colon, rectal lesions, and a larger lesion in the liver.

OUTCOME

After treatment, although the thyroid globulin remained at a high level 3 months after treatment, the patient's hematochezia was relieved.

LESSONS

Therefore, thyroidectomy followed by adjuvant I treatment should be recommended in patients with malignant struma ovarii as metastatic risk is difficult to predict based on histopathologic examination.

131I therapy using rhTSH stimulation and dosimetry in metastatic malignant struma ovarii

A 38-year-old woman with metastatic malignant struma ovarii, including massive liver metastases and retroperitoneal lymphadenopathy, underwent ovarian resection and retroperitoneal lymph nodes excision, partial hepatectomy, and radiofrequency ablation for liver metastases. She underwent thyroidectomy and received three I treatments using recombinant human thyrotropin stimulation and radioiodine dosimetry. posttherapy I imaging, anatomic images, and thyroglobulin levels showed significant diminution in the tumor burdens and remarkable decline in thyroglobulin levels. This case provided valuable information on recombinant human thyrotropin-assisted I ablation in conjunction with dosimetry in an unusual presentation of iodine-avid malignant struma ovarii with bulky metastases.

Delayed treatment of papillary thyroid carcinoma arising from struma ovarii in a patient with history of bilateral salpingo-oophorectomy: a case report

OBJECTIVE

We present a case of papillary thyroid carcinoma arising from struma ovarii treated erroneously as ovarian adenocarcinoma for more than 3 years.

METHODS

We report clinical, surgical, laboratory, and imaging findings of the study patient and review the relevant literature.

RESULTS

A 64-year-old woman was treated for ovarian adenocarcinoma for more than 3 years before it was determined that she likely had papillary thyroid carcinoma arising from struma ovarii. This is the first reported case of thyroid carcinoma arising from struma ovarii in a patient with a history of bilateral salpingo-oophorectomy. Possible etiologies include residual ovarian tissue after oophorectomy, ectopic thyroid, or metastatic thyroid cancer.

CONCLUSIONS

It is important to include struma ovarii and thyroid carcinoma arising from struma ovarii in the differential diagnosis, even with a history of bilateral salpingo-oophorectomy. This case emphasizes the importance of effective communication among the pathologist, oncologist, and surgeon to ensure timely initiation of appropriate therapy and reduced patient morbidity.

Optimal surgical management of well-differentiated thyroid cancer arising in struma ovarii: a series of 4 patients and a review of 53 reported cases

BACKGROUND

Well-differentiated thyroid cancer arising in struma ovarii is rare. The optimal management of this entity remains undefined. Unilateral cystectomy, unilateral salpingo-oophorectomy (USO), or total abdominal hysterectomy with bilateral salpingo-oophorectomy (TAH/BSO), in addition to total thyroidectomy and radioactive iodine (RAI) ablation, have been employed by various groups. We hypothesized that in patients with thyroid cancer arising within struma ovarii, pelvic surgery alone would be sufficient, provided there is no evidence of gross extra-ovarian extension.

METHODS

We review a series of four patients from a single institution and 53 cases from the literature, comparing the extent of treatment and outcomes. Our literature review focused on low-risk patients with struma ovarii confined to the ovary, without evidence of gross extra-ovarian spread or distant metastases. Cumulative recurrence rate was determined by using the Kaplan-Meier method.

RESULTS

We report the treatment of four patients with well-differentiated thyroid cancer arising within struma ovarii. Patients underwent USO, BSO, or TAH/BSO. One patient underwent prophylactic total thyroidectomy in anticipation of RAI treatment, and was found to have a synchronous papillary thyroid carcinoma. All patients clinically remain without evidence of disease at a median follow-up of 9 (range 0.8-13) years. Treatment strategies in 53 cases from a review of the literature varied. The pooled cumulative recurrence rate of 57 cases with struma ovarii confined to the ovary was 7.5% at 25 years.

CONCLUSIONS

Thyroid cancer arising in struma ovarii is rare. Controversy exists regarding the extent of pelvic resection and management of the thyroid gland. In our series of four patients, all patients are alive without evidence of disease, and the 25-year recurrence rate of 57 cases was low (7.5%), despite a variety of approaches to surgical resection and adjuvant treatment. Extensive pelvic surgery and prophylactic total thyroidectomy to facilitate RAI therapy may be reserved for patients with gross extra-ovarian extension or distant metastases.