Malignant Struma Ovarii: An Analysis of 88 Cases, Including 27 With Extraovarian Spread:

Personalized approach to malignant struma ovarii: Insights from a web-based machine learning tool

OBJECTIVES

Malignant struma ovarii (MSO) is a rare ovarian tumor characterized by mature thyroid tissue. The diverse symptoms and uncommon nature of MSO can create difficulties in its diagnosis and treatment. This study aimed to analyze data and use machine learning methods to understand the prognostic factors and potential management strategies for MSO.

METHODS

In this retrospective cohort, the Surveillance, Epidemiology, and End Results (SEER) database provided the data used for this study's analysis. To identify the prognostic variables, we conducted Cox regression analysis and constructed prognostic models using five machine learning algorithms to predict the 5-year survival. A validation method incorporating the area under the curve of the receiver operating characteristic curve was used to validate the accuracy and reliability of the machine learning models. We also investigated the role of multiple therapeutic options using the Kaplan-Meier survival analysis.

RESULTS

The study population comprised 329 patients. Multivariate Cox regression analysis revealed that older age, unmarried status, chemotherapy, and the total number of tumors in patients were poor prognostic factors. Machine learning models revealed that the multilayer perceptron accurately predicted outcomes, followed by the random forest classifier, gradient boosting classifier, K-nearest neighbors, and logistic regression models. The factors that contributed the most were age, marital status, and the total number of tumors in the patients.

CONCLUSION

The present study offers a comprehensive approach for the treatment and prognosis assessment of patients with MSO. The machine learning models we have developed serve as a practical, personalized tool to aid in clinical decision-making processes.

A rare case of retroperitoneal teratoma with evidence of papillary thyroid carcinoma: a case report

BACKGROUND

Teratomas are germ cell tumors composed of somatic tissues from up to three germ layers. Primary retroperitoneal teratomas usually develop during childhood and are uncommon in adults and in the retroperitoneal space. While there are only a few cases of retroperitoneal thyroid tissue, we report a unique case of a retroperitoneal papillary thyroid carcinoma.

CASE PRESENTATION

A 41-year-old woman presented in our institution due to intermitted unspecific abdominal pain. Magnetic resonance imaging detected a multi-cystic solid retroperitoneal mass ventral to the psoas muscle and the left iliac artery. After surgical removal of the retroperitoneal mass, histology sections of the specimen indicated evidence of papillary thyroid carcinoma cells. A staging computed tomography scan of the body showed no further manifestations. To reduce the risk of recurrence, total thyroidectomy was performed followed by radioiodine therapy with lifelong hormone substitution.

CONCLUSIONS

Primary retroperitoneal teratoma with evidence of papillary thyroid carcinoma is a rare condition. Preoperative diagnosis is difficult due to its non-specific clinical manifestation and lack of specific radiologic findings. Histopathology analysis is necessary for diagnosis. Although surgery is considered the first line treatment, there is still discussion about the extent of resection and the need for total thyroidectomy with adjuvant radioiodine therapy.

Metastatic malignant struma ovarii to the pituitary presenting as a sellar mass and responding to total thyroidectomy with adjuvant radioactive iodine therapy

Malignant struma ovarii (MSO) is a rare ovarian teratoma composed primarily of thyroid tissue. Common sites of metastasis include peritoneum, bone, liver, lung, gastrointestinal tract and omentum. We present a woman in her 50s with a history of remote oophorectomy presenting with hypopituitarism and a 2.7 cm sellar mass. Trans-sphenoidal surgery for presumed pituitary macroadenoma achieved near total resection and resultant pathology surprisingly showed ectopic thyroid tissue. The patient acquired her ovarian pathology report from Southeast Asia which showed struma ovarii of the left ovary. The pituitary mass was thus determined to be a metastatic lesion from MSO. She underwent total thyroidectomy and radioactive iodine ablation therapy with good initial response and no regrowth of the tissue or emergence of distant metastases after 5 years of annual follow-up. To our knowledge, this is the first reported case of MSO to the pituitary.

Clinical Manifestations of Malignant Struma Ovarii: A Retrospective Case Series in a Tertiary Hospital in Korea

BACKGRUOUND

Malignant struma ovarii (MSO) is a very rare disease in which thyroid cancer originates from the ovary. Because it is rare for endocrinologists to encounter patients with MSO, endocrinologists may have a limited understanding of the disease. Therefore, we analyzed and introduced its incidence and clinical course in a tertiary hospital in Korea.

METHODS

We retrospectively investigated the clinical data of 170 patients who underwent surgery for struma ovarii at the Department of Obstetrics and Gynecology of Samsung Medical Center from 1994 to May 2023.

RESULTS

Among 170 patients with struma ovarii, 15 (8.8%) were diagnosed with MSO. The median age of patients with MSO was 48 years (range, 30 to 74), and the median tumor size was 3.3 cm (range, 0.5 to 11.0). Papillary thyroid carcinoma (46.7%) was the most common subtypes followed by follicular thyroid carcinoma (26.7%). All patients were diagnosed after surgery, with no predictions from preoperative imaging. The surgical extent of gynecological surgery was variable. Four patients (26.7%) underwent thyroidectomy for thyroid cancer, while one underwent total thyroidectomy and radioactive iodine therapy for MSO with peritoneal metastasis. Except for one patient who underwent hemithyroidectomy, thyroid stimulating hormone suppression therapy was performed in four patients. Only 53% of MSO patients were consulted by an endocrinologist. With a median follow-up period of 33 months (range, 4 to 156), 11 patients remained disease-free, one experienced progression with peritoneal seeding, and the remaining one was in treatment. There have been no recurrences or deaths due to MSO.

CONCLUSION

An endocrinologist should be involved in establishing a therapeutic plan for MSO, for which the overall prognosis is generally favorable.

Highly differentiated follicular carcinoma of the ovary with omental and peritoneal spread in a 22-year-old girl; A diagnostic and counseling challenge

INTRODUCTION AND IMPORTANCE

Highly differentiated follicular carcinoma of the ovary (HDFCO) is a rare type of thyroid carcinoma originating from struma ovarii, consisting of benign-appearing thyroid follicles spread outside the ovarian tissue.

CASE PRESENTATION

We present a 22-year-old girl who underwent left salpingo-oophorectomy, omental, and peritoneal biopsies for a complex left ovarian mass. Microscopic examination and Immunohistochemical staining led to the diagnosis of HDFCO with tumor deposits affecting the omental and peritoneal biopsies. The patient was counseled about the nature of her disease and the recommended treatment. Thyroidectomy was performed later, revealing a normal thyroid gland. The patient received an ablative dose of radioactive iodine (150 mci) and a suppressive dose of levothyroxine. This is one of the youngest reported patients ever.

CLINICAL DISCUSSION

To our knowledge, the patient presented in this case report is one of the youngest patients ever reported in the literature. In the recent WHO Classification of Female Genital Tumors, the term highly differentiated follicular carcinoma arising from struma ovarii (HDFCO) was introduced, to emphasize its low-grade malignant behavior. Due to its rare incidence, there is no standard treatment strategy, but a plan based on surgical intervention is suggested.

CONCLUSION

Malignant struma ovarii should be put in the differential diagnosis in young patients with suspicious ovarian masses. Adequate patient counseling remains a cornerstone in the journey of management.

A Curious Case of Omental Oxalate Crystals in a Patient With Struma Ovarii: Pointers to an Unusual Clinicopathological Scenario

Percutaneous image-guided biopsies are becoming increasingly common in routine pathology practice, with the greater omentum emerging as a common target. We present herein an account of a middle-aged lady with a complex ovarian mass, omental thickening, and raised serum CA125; clinically suspected to have advanced ovarian malignancy. Fine needle aspiration cytology (FNAC) from the ovarian mass was inconclusive. Omental biopsy revealed only refractile, birefringent crystalline material with surrounding foreign body giant cell reaction; thus surprising the clinical team. Subsequent resection of the ovarian mass showed a teratoma composed exclusively of thyroid tissue, diagnosed as struma ovarii. The omental crystals, interpreted as calcium oxalate crystals, were possibly a consequence of colloid seeding during the ovarian mass FNAC.

Role of gene sequencing in classifying struma ovarii: BRAF p.G469A mutation and TERT promoter alterations favour malignant struma ovarii

AIMS

Struma ovarii (SO) are rare, accounting for 0.3-1% of ovarian tumours, and include benign and malignant lesions. In most cases, histology is not predictive of clinical outcome and prognosis. The prognosis of histologically malignant thyroid-type carcinomas can indeed be excellent, while SO, composed of normal thyroid tissue, can recur and are designated highly differentiated follicular carcinoma of the ovary. Clearer diagnostic criteria are therefore required.

METHODS AND RESULTS

We retrospectively studied 31 SO using DNA and RNA sequencing with pan-cancer gene panels, including eight biologically malignant SO (BMSO) defined based on ovarian serosal or extra-ovarian dissemination at presentation or during follow-up, 10 stage IA histologically malignant SO (HMSO) with thyroid-type carcinoma morphology and 13 biologically and histologically benign SO (BSO), with none of the above-mentioned characteristics. Molecular alterations were observed in 87.5% of BMSO, 70% of HMSO and 7.7% of BSO (P < 0.001). All patients with a peritoneal dissemination at presentation or during follow-up had at least one gene alteration. BRAF mutations (44.5%) were only observed in malignant forms (HMSO and BMSO) and TERT promoter alterations (25%) only in cases of BMSO. The BRAF p.G469A mutation, which is extremely rare in thyroid carcinomas, was the molecular alteration most frequently associated with malignant SO (28.5%).

CONCLUSION

Our results highlight the clinical utility of molecular sequencing in SO, based on this limited number of cases. However, as malignant SO evolve slowly, more extensive molecular studies in SO with more than 10 years' follow-up are required to draw any conclusions on the prognostic value of the associated gene alterations.

Neoplasms in Struma Ovarii: A Review

Struma ovarii is a well-known ovarian teratoma made up of benign thyroid tissue. These lesions demonstrate variable, normal architecture and normal thyroid immunohistochemical staining with positivity for TTF1, PAX8, and thyroglobulin. Though most are benign, some of these lesions can also present with a malignant component. Within this article, we review the most common diagnostic malignancies including papillary thyroid carcinoma, strumal carcinoid, highly differentiated follicular thyroid carcinoma, and other thyroid carcinomas. We additionally review the use of TTF1 staining to assist in differentiating these lesions from surrounding gynecologic epithelium, which is imperative in making such diagnoses. In highlighting these entities, we hope to provide practicing pathologists with an effective and concise review of these lesions to assist in more challenging cases of struma ovarii.

Thyroid Carcinoma Arising From Struma Ovarii at Adolescence: A Challenging Case With Favorable Outcome

Malignant struma ovarii (MSO) is a rare and aggressive ovarian tumor that mostly affects adults but can occur in adolescents. Prompt recognition, accurate diagnosis, and multidisciplinary management are essential for favorable outcomes. Herein, we report the youngest case of an 11-year-old girl with a large MSO. First, conventional imaging revealed a large left ovarian mass, leading to a left oophorectomy. Subsequently, histopathological examination confirmed papillary thyroid carcinoma within MSO. Thyroid and fertility-preserving surgery were chosen after multidisciplinary consultation. Despite challenges, the patient had a positive outcome with no recurrence after 36 months. Therefore, the adoption of less invasive surgical approaches and vigilant follow-up can achieve remission, but more research is needed to further enhance our understanding of the disease's risk stratification and optimal treatment strategies.

Mature cystic teratoma of the ovary with malignant transformation of tall cell subtype of papillary thyroid carcinoma

Malignancies rarely occur in somatic parts of mature cystic teratoma of the ovary. Squamous cell carcinoma is the most common form of cancer that can develop in mature cystic teratoma. Other less frequent malignancies include melanoma, sarcoma, carcinoid, and germ cell neoplasms. Only three cases have been reported as papillary thyroid carcinoma arising in struma ovarii. We present a unique case of a 31-year-old female patient who presented with a left ovarian cyst and underwent conservative surgical management in the form of cystectomy. Histopathological examination confirmed the diagnosis of a tall cell subtype of papillary thyroid carcinoma arising from a small focus of thyroid tissue in a mature cystic teratoma of the ovary. The patient was followed up for 60 months with an uneventful clinical course. For a better understanding of such rare cancers, collaborative retrospective studies on large databases with other medical centers are required.

It Does Exist! Diagnosis and Management of Thyroid Carcinomas Originating in Struma Ovarii

Thyroid carcinoma originating in struma ovarii comprises a small minority of all cases of struma ovarii. Given the rarity of this diagnosis, literature to guide evaluation and management is limited. The most common carcinoma originating from struma ovarii is papillary thyroid carcinoma. Treatment includes surgery, including a fertility sparing approach if disease is confined to the ovary, with consideration of total thyroidectomy and radioactive iodine ablation for high-risk pathologic features or disease spread beyond the ovary. This review discusses the histopathologic findings, molecular pathology, clinical implications and management, and prognosis of thyroid carcinomas originating in struma ovarii.

Malignant Struma Ovarii (Papillary Carcinoma) with Hyperthyroidism: A Case Report and Literature Review

Malignant struma ovarii (MSO) is an extremely rare monodermal ovarian teratoma. Preoperative diagnosis and intraoperative freezing diagnosis are exceedingly difficult due to the rarity of the disease and its clinically noncharacteristic manifestations with less than 200 reports in the current literature. In this paper, a case of MSO (papillary carcinoma) with hyperthyroidism was discussed in terms of its epidemiology, clinicopathology, molecular features, treatment, and prognosis.

Germ Cell Tumors of the Ovary: A Review

Ovarian germ cell tumors are a diverse group of benign and malignant neoplasms that occur in a wide age range, but with a predilection for younger age group. The majority are represented by the frequently encountered mature cystic teratomas. Malignant germ cell tumors are uncommon, and in some cases have a characteristic clinical presentation. However, from a histologic standpoint these tumors can sometimes be challenging to diagnose due to overlapping morphology with epithelial, and in some cases sex cord tumors. In these cases, a panel of immunohistochemical stains often facilitates the correct diagnosis. This review article discusses the clinicopathologic findings and pertinent ancillary studies of both common and uncommon germ cell tumors of the ovary.

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 thyroid-type papillary and poorly differentiated carcinoma: a case report

Background

Malignant struma ovarii is a very rare type of gynecologic cancer. Although its most common histological subtype is a pure type of papillary thyroid carcinoma containing two components, papillary carcinoma and poorly differentiated carcinoma, malignant struma ovarii is still extremely rare. As a result, the optimal treatment for this type of tumor remains uncertain due to its rarity.

Case presentation

A 62-year-old Japanese female presented with a pelvic tumor and clinical diagnosis of malignant tumor of the ovary. She underwent complete debulking surgery, total abdominal hysterectomy, bilateral salpingo-oophorectomy, and omentectomy. The histology of the ovarian tumor revealed malignant struma ovarii with thyroid-type papillary projections and poorly differentiated carcinoma. Because of the complete resection and the absence of distant metastasis, the patient did not receive any adjuvant therapy. At 24 months after surgery, she was free of disease.

Conclusion

This is a rare case report of malignant struma ovarii, without recurrence, in which the component was papillary thyroid carcinoma mixed with poorly differentiated carcinoma. Foregoing adjuvant therapy might be one option for malignant struma ovarii in cases with complete resection and no distant metastasis. In addition, we should consider that long-term follow-up is needed for malignant struma ovarii.

Proposed Risk Stratification and Patterns of Radioactive Iodine Therapy in Malignant Struma Ovarii

Introduction: Malignant struma ovarii (MSO) is a rare thyroid cancer arising within an ovarian teratoma. While surgical excision of the primary tumor is widely accepted as standard of care, recommendations for adjuvant treatment of MSO-whether or not to administer radioactive iodine (RAI)-are based largely on case reports and remain debated. In this study, we aimed to propose a risk stratification and analyze RAI utilization patterns in MSO cases. Methods: The National Cancer Database (NCDB) was queried for patients with MSO between 2004 and 2016. Demographic, oncological, and clinicopathologic data were compared between groups using Fisher's exact test. Kaplan-Meier curves were used to estimate overall survival (OS), and variables associated with OS were assessed via univariate Cox regression. We adapted the 2015 American Thyroid Association risk guidelines for MSO patients. We stratified patients into low-, intermediate-, and high-risk groups using metastasis, extraovarian extension, lymphovascular invasion, lymph node status, surgical margins, tumor size, and grade. Risk stratification, demographic, oncological, and clinicopathologic data were compared between the groups receiving and not receiving RAI therapy. We then queried the Surveillance, Epidemiology, and End Results (SEER) 18 registry for patients with MSO between 2000 and 2018 to confirm our risk stratification analysis. Results: In the NCDB analysis, a total of 158 patients were identified, and 19 received RAI. RAI therapy was associated with distant metastasis (p = 0.005) and lymph node status (p = 0.012). Twenty-one NCDB patients were stratified as high risk, and 30% of high-risk patients received RAI. High-risk stratification was associated with decreased OS via univariate Cox regression (hazard ratio = 4.0 [95% confidence interval 1.11-14.26], p = 0.034). In our subsequent analysis using the SEER registry, there were 95 MSO patients, and 18 received RAI. Again, the majority of high-risk patients did not receive RAI, with only 41% of high-risk patients receiving RAI. Conclusions: MSO is a rare malignancy with apparently variable and inconsistent patterns of postoperative RAI administration. The risk stratification described here provides a framework to identify patients potentially at risk for mortality, and utilization of RAI in this group should be studied further.

Management of malignant struma ovarii: is aggressive therapy justified? Case report and literature review

Background

Struma ovarii (SO) is a rare ovarian teratoma containing predominantly thyroid tissue. In rare situations SO may develop malignancy. Most cases of malignant struma ovarii (MSO) are diagnosed after surgical removal, based on histopathological examination. There are still controversies regarding the extent of surgery and postoperative management in MSO, due to its unpredictable behavior, possible risk of metastasis and relatively high rate of recurrence.

Case Presentation

We present the case of a patient diagnosed with a right ovarian cyst discovered incidentally during routine ultrasound examination. Its rapid growth and pelvic MRI raised the suspicion of a neoplastic process. She underwent total hysterectomy and bilateral adnexectomy. The anatomopathological diagnosis was MSO with follicular variant of papillary thyroid carcinoma. Prophylactic total thyroidectomy was performed, followed by radioactive iodine ablation (RAI), and suppressive therapy with levothyroxine. At 1 year follow-up, the patient was disease free.

Conclusions

Even if latest literature reports consider that completion of local surgery with total thyroidectomy and RAI might be too aggressive in cases of MSO without extraovarian extension, in our case it was decided to follow the protocol for primary thyroid carcinoma, in order to reduce the recurrence risk.

Malignant Clinical Course of "Proliferative" Ovarian Struma: Diagnostic Challenges and Treatment Pitfalls

Struma ovarii (SO) is a monodermal teratoma predominantly composed of thyroid tissue (TT) showing benign, “proliferative”, or malignant histology. By imaging, a 38-year-old patient with lower backache revealed a 6.2-cm vertebral lesion (L5). Core biopsy showed well-differentiated TT without features of papillary carcinoma. A 3.5-cm left ovarian mature teratoma (lacking TT) and peritoneal nodules (showing well-differentiated TT) were also identified and surgically removed. Thyroid ultrasound and cytological examination resulted negative. Four years before, left ovarian cystectomy was performed for a histologically “proliferative” SO. According to the malignant clinical course and WHO classification, this case was overall reassessed as a recurring well-differentiated follicular carcinoma arising in SO (WD-FC-SO), despite lacking malignant histological features in any specimens. Immunophenotype: TTF-1+/PAX-8+/thyroglobulin+/CK7+/chromogranin-/synaptophysin-/inhibin-/calretinin-/HNF1B-; Ki-67 index < 5%. Polymerase chain reaction analysis resulted negative for BRAFV600E mutation. The patient refused further treatments, without recurrence after 17 months. The clinical behavior of SO may be unpredictable. Histologically benign or proliferative strumas extraordinarily metastasize, while SO with malignant features may not recur. The exceptional evidence of peritoneal implants of well-differentiated TT (peritoneal strumosis) in patients with histologically benign SO represents a metastasis of WD-FC-SO (like in our case). A multidisciplinary approach including clinical, laboratory, radiologic, and histopathological data is required.

Metastatic follicular carcinoma arising from struma ovarii

Struma ovarii (SO) is an uncommon monodermal teratoma predominantly composed of mature thyroid tissue. Approximately 5% of SO are malignant; however, metastases are rare. A single female in her 40s, with a medical history of Graves' disease and bilateral cystectomy 10 years prior for right endometriotic cyst and left SO, presented with an enlarging abdominal mass for 4 months. Ultrasound pelvis showed a 13.8 cm left adnexal heterogeneous solid-cystic mass with internal septations and vascularity. She underwent open left salpingo-oophorectomy and resection of fibrous nodules from the right infundibulo-pelvic ligament and fallopian tube. Histology showed highly differentiated metastatic follicular carcinoma. She subsequently underwent total thyroidectomy, total hysterectomy, right salpingo-oophorectomy, tumour debulking and omentectomy followed by radioactive iodine treatment. Four-year follow-up did not show tumour recurrence or metastases. Due to its rarity, there are no well-established guidelines for the management and follow-up of metastatic follicular carcinoma arising from SO.

Spontaneous expression of the gene of KI67 and P53 in cynomolgus monkeys infected with papillomavirus

Background and Aim: Cynomolgus monkeys (Macaca fascicularis) develop spontaneous infection of Papillomavirus (PV); thus, potentially beneficial for modeling human PV (HPV) infection study. Contrary to human origin, infection in cynomolgus monkeys does not always show evident clinical symptoms of cervical cancer. The absence of cervical cancer clinical symptoms leads us to investigate the molecular mechanism of the HPV infection in cynomolgus monkeys. This study aimed to investigate the messenger ribonucleic acid (mRNA) expression levels of KI67 and P53 genes, majorly known as biomarker oncogenesis of PV infection. Materials and Methods: The polymerase chain reaction (PCR) technique was used with MY11/MY09 primer to screen PV in cynomolgus monkey, further grouped as positive-PV and negative-PV infection groups. Real-time quantitative PCR was also applied to quantify the mRNA expression levels of KI67 and P53 genes in animals. Results: Increased expression of mRNA level of KI67 genes was significantly higher in Positive- PV group than negative-PV group. In contrast, the P53 mRNA expression level increased markedly higher in the negative-PV group than in the positive-PV group. Conclusion: Our study describes the potential of cynomolgus monkeys as a spontaneous oncogenesis model of PV infection-type. However, we used a limited number of cancer genetic markers. So, further study of other genetic markers is required to prove that cervical cancer could be developed naturally in cynomolgus monkeys.

Malignant struma ovarii with papillary carcinoma combined with retroperitoneal lymph node metastasis: A case report

BACKGROUND

Struma ovarii is a rare specific ovarian tumor. It is a highly differentiated monodermal teratoma with a malignant transformation rate as low as 5%. Thus, malignant transformation and metastasis are extremely rare. The clinical manifestations of this disease are not typical and are easily misdiagnosed.

CASE SUMMARY

A 55-year-old female patient had a history of pain in the right hepatic region for approximately 1 year. Computed tomography and magnetic resonance imaging showed a solid cystic mass in the right adnexal region and a solid mass in the right retroperitoneum. The patient underwent surgical resection, and the combined morphological and immunohistochemical results led to the final diagnosis of right struma ovarii with papillary carcinoma and right retroperitoneal lymph node metastasis.

CONCLUSION

Malignant struma ovarii with distant metastasis is extremely rare, and the clinical manifestations of this disease are nonspecific. Accurate preoperative diagnoses are difficult to obtain, and pathological examination is the gold standard for diagnosing this disease.

[Rare kidney tumor - thyroid-like follicular carcinoma]

The literature review provides an analysis of a rare malignant tumor of the kidney: thyroid-like follicular carcinoma of the kidney (TLFCK). In morphology, this tumor is extremely similar to thyroid follicular carcinoma, but the immunophenotype of tumor cells is different. TLFCK has an indolent clinical course, rarely metastasizes, and even the development of metastases does not mean an unfavorable prognosis for the patient. The literature review presents the features of the clinical course of the disease, macroscopic, microscopic, immunohistochemical characteristics of the tumor and typical cytogenetic breakdowns. Particular attention is paid to the issues of differential diagnosis of the tumor with other pathological processes that may microscopically resemble TLFCK.

Survival Outcomes and Prognostic Predictors in Patients With Malignant Struma Ovarii

Background: Malignant struma ovarii (MSO) is an extremely rare ovarian malignant tumor and there is limited data on the survival outcomes and prognostic predictors of MSO. The objectives of this study were to investigate the disease-free survival (DFS), overall survival (OS), and disease-specific survival (DSS) rates of patients with MSO, and also evaluate the prognostic factors in this population.

Methods: A retrospective study was conducted and 194 cases of MSO were selected. DFS was assessed by the logistic regression, OS by the Kaplan–Meier method, and DSS was evaluated by the Cox regression.

Results: The median age of these patients was 46.0 years; 142 cases (73.2%) were confined to the ovary and 52 cases (26.8%) had extraovarian metastasis at the initial diagnosis of MSO. During the follow-up, 75.3% of these patients showed no evidence of disease and 18.0% were alive with disease. Only 13 deaths occurred, with 10 attributed to MSO. The 5, 10, and 15-year OS rates were 91.4, 87.7, and 83.5%, respectively. The 5, 10, and 15-year DSS rates were 93.8, 90.0, and 85.7%, respectively. Logistic regression revealed that International Federation of Gynecology and Obstetrics (FIGO) stage IV was the only risk factor for DFS [p < 0.001; odds ratio (OR) 7.328; 95% CI 3.103–16.885, FIGO stage IV vs. stage I; p = 0.021; OR 4.750, 95% CI 1.264–17.856, FIGO stage IV vs. stage II-III]. The multivariate Cox regression analysis showed that poor differentiation was the only risk factor for both OS (p = 0.005, OR 6.406; 95% CI 1.730–23.717) and DSS (p = 0.001, OR 9.664; 95% CI 2.409–38.760), while age ≥45 years was the prognostic predictor for OS (p = 0.038, OR 4.959; 95% CI 1.093–22.508).

Conclusion: Survival outcomes were excellent in patients with MSO, irrespective of the treatment strategy, FIGO stage IV, age ≥45 years, and poor differentiation of tumors were the independent risk factors.

Huge follicular carcinoma originated from struma ovarii in young woman; Extremely rare case

Introduction

Struma ovarii (SO) is a rare ovarian mature teratoma which is composed of 50% or more thyroid tissues. Malignant transformation is reported to occur in less than 5% of all cases, and it leads to 5-6% metastatic disease. The most common type is a papillary carcinoma. However, follicular carcinoma of arising from SO is extremely rare.

Case presentation

A 23-year-old nullipara complained of right lower abdominal pain. CT scan revealed a large complex cystic and solid mass in pelvic cavity with moderate amount ascites with peritoneal thickening and omental infiltration. We performed a right salpingo-oophorectomy and surgical staging.

Clinical discussion

It was diagnosed with follicular carcinoma, stage IA. After the multidisciplinary team meeting, we decided not to conduct additional treatment, including total thyroidectomy followed by radioiodine treatment and T4 therapy because thyroid tests were normal findings.

Conclusion

There is still no established treatment consensus for follicular carcinoma of SO patients. The choice for a conservative or radical approach depends on the doctor. However, conservative surgery could be considered for low risk, early stage patients who have childbearing potential.

PET/CT Variants and Pitfalls in Gynecological Cancers

The role of hybrid imaging with 2-[18F] flourodeoxyglucose (FDG) positron emission tomography and computed tomography (PET/CT) is continuously evolving and now considered standard practice in evaluation of disease stage, treatment response, recurrent disease and follow-up for numerous primary malignancies. In gynecological malignancies FDG PET/CT plays an important role, not only in the assessment of disease in the pre-and post-therapy setting, but also in radiation therapy (RT) planning by defining the metabolically active gross tumor volume (GTV. The glucose analogue radiotracer, FDG, is by far the most utilized radiotracer in PET/CT and is typically seen with high uptake in malignant cells. The radiotracer FDG has a high sensitivity but low specificity for malignancy, as benign processes with an inflammatory response for example infection, are also FDG-avid. In the evaluation of the female pelvic region an awareness of potential confounding factors in the interpretation of FDG is essential as variations of FDG uptake occur in accordance with the menstrual cycle and the menopausal state. Incidental imaging findings in the female genital can pose differential diagnostic challenges as false-positive and false-negative findings in benign and malignant processes are not uncommon. Gynecological malignancies continue to pose major public health problems with cervical cancer as the fourth most common cancer in women ranking after breast cancer, colorectal cancer and lung cancer. Familiarity with frequently encountered benign and malignant variants and pitfalls in FDG PET/CT in the female pelvic region can aid the reader in differential diagnostic considerations.

Malignant struma ovarii: From case to analysis

AIM

To evaluate the clinico-pathologic features, treatment options, prognostic factors, and survival outcomes of malignant struma ovarii based on a systematic literature review in association with our case study.

METHODS

A systematic review of the medical literature was performed to identify articles about malignant struma ovarii from January 1983 until July 2020. We evaluated 178 cases.

RESULTS

The 5-year progression-free survival (PFS) and overall survival (OS) of the entire cohort was 72.5% and 91%, respectively. In univariate analysis, younger age (<43 years), whole strumal cyst diameter >95 mm, presence of a histologic type other than papillary classic-type thyroid carcinoma within the tumor and lymphovascular space invasion were related to poor PFS. Patients who received radioactive iodine ablation (RIA) before the treatment failure had significantly higher PFS than those who did not receive RIA (94.9% vs. 64.8%, p = 0.041, respectively). In univariate analysis, PFS was significantly higher in patients who underwent gynecologic surgery followed by thyroidectomy and RIA compared with those who had surgical treatment only (94.5% vs. 64.3%, p = 0.05, respectively). However, this result could not be identified as an independent prognostic factor in multivariate analysis (p = 0.207). Younger age and absence of capsular involvement were related to significantly increased OS. Histologic type was the only independent prognostic factor for PFS (hazard ratio: 3.30, 95% confidence interval: 1.122-9.748; p = 0.030) CONCLUSION: The most common histologic subtype was the papillary classic type. The presence of a histologic type other than the classic papillary thyroid carcinoma within the tumor was an independent adverse prognostic factor.

Malignant struma ovarii with late recurrence harbouring high microsatellite instability

Struma ovarii (SO) is a rare ovarian teratoma containing abundant mature thyroid tissue. Malignant transformation is even less common and distant metastasis is documented in about 5%-10%. The time from diagnosis of primary SO to metastatic disease varies. As malignant SO is rare, there are no uniform diagnostic criteria or treatment guidelines. Management is usually extrapolated from that of thyroid malignancy. We report a patient who relapsed 12 years from the initial diagnosis and metastasised to the lungs 5 years after the first recurrence. Our patient was treated with total thyroidectomy followed by radioactive iodine, and retreated on progression in the lungs. The tumour harboured high microsatellite instability and treatment with programmed cell death protein 1 inhibitor was initiated. This case shows the long latency of SO with the rare phenomenon of metastasis. It also highlights the importance of molecular testing for rare cancers such as this.

Ovarian teratomas: clinical features, imaging findings and management

Ovarian teratomas are the most common type of germ cell tumors. There are three major subtypes of ovarian teratomas including mature, immature, and monodermal teratomas. Ultrasound, computed tomography and magnetic resonance imaging can demonstrate specific imaging findings for mature teratoma. Imaging features of immature and monodermal teratomas are less specific, but a combination of clinical features and imaging findings can help in the diagnosis. Imaging is also very helpful in guiding management. In this article, we review the epidemiology, histopathology, clinical presentation, imaging features and management of ovarian teratomas.

Clinical characteristics and survival outcomes of malignant struma ovarii confined to the ovary

Background

Malignant struma ovarii (MSO) is a unique type of ovarian malignancy that data on the survival outcome is limited and management strategy remains controversial due to its extreme rarity.

Methods

To investigate the clinical characteristics and treatment options in patients with MSO confined to the ovary, while also evaluating the recurrent-free survival (RFS) and overall survival (OS) rate in this population, a retrospective study was conducted. One hundred twenty-five cases of MSO confined to the ovary were enrolled and their clinical characteristics, treatment strategies, and results of follow-up were analyzed. OS and RFS were assessed by Kaplan-Meier analyses and Cox regression models.

Results

The most common pathological subtype in this cohort was papillary carcinoma (44.8%). Other reported subtypes, in order of prevalence, were follicular variant of papillary carcinoma, follicular carcinoma, and mixed follicular-papillary carcinoma. Surgical treatment options varied in this cohort that 8.0% of the patients received ovarian cystectomy, 33.6% underwent unilateral salpingo-oophorectomy (USO), 5.6% received bilateral salpingo-oophorectomy (BSO), 21.6% received total abdominal hysterectomy with BSO (TAH/BSO), and 17.6% were treated with debulking surgery; 20.0% of them received radioiodine therapy (RAI). Twenty-seven patients experienced recurrence with a median RFS of 14.0 years (95% confidence interval [CI], 9.5–18.5). The 5-year and 10-year recurrent rate were 27.1, 35.2%, respectively. Eight patients died during follow-up, with five attributed to MSO; the 5-year, 10-year, and 20-year OS rate was 95.3, 88.7 and 88.7%, respectively. However, the univariate and multivariate Cox regression showed no potential risk factor for RFS and OS.

Conclusion

Patients with MSO confined to the ovary had an excellent survival outcome, despite varied treatment strategies, and the recurrent rate was relatively high. We recommend USO as the preferred surgical option in this population since more aggressive surgery does not improve outcomes and the benefits of RAI are uncertain.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08118-7.

The Clinical and Pathological Characteristics of Malignant Struma Ovarii: An Analysis of 144 Published Patients

The objective of this study is to summarize the clinical and pathologic characteristics of malignant struma ovarii to facilitate the early diagnosis and treatment of this disease. All 144 patients were females from 27 countries. The mean age of the patients at diagnosis was 42.6 years. Overall, 35.71% of the patients underwent unilateral oophorectomy, 58.57% of the patients underwent bilateral oophorectomy, 5.72% of the patients were not ovariectomized, and 38.57% of the patients received radioactive iodine treatment with an average dose of 158.22 mCI each time. “Impure” types accounted for 70.19% of the cases, while pure types accounted for 29.81% of the cases. Among these cases, papillary thyroid carcinoma accounted for 50.00%, follicular thyroid carcinoma accounted for 26.47%, follicular variant of papillary thyroid carcinoma accounted for 18.63%, papillary and follicular mixed thyroid carcinoma accounted for 2.94%, anaplastic carcinoma accounted for 0.98%, and medullary carcinoma accounted for 0.98%. In total, 21 patients (51.22%) had elevated CA125. More than half of the patients (51.94%) had metastasis outside the ovary. The most common metastatic site was the pelvic cavity. The misdiagnosis rate was 17.27%. Mortality was related to metastasis and the cancer type. Gene mutations were found in the NRAS, KRAS, BRAF, and KIT genes and were similar to those in thyroid carcinoma, but some patients (37.5%) did not exhibit any gene mutations. Regardless of the treatment received, the survival rate is high. Treatment could initially include ovariectomy; however, in cases with metastasis and iodine uptake of the metastatic tumor, thyroidectomy, radioactive iodine therapy, and thyroid hormone inhibiting therapy are indicated.

Metastatic Malignant Struma Ovarii and Graves' Disease: A Rare Occurrence

Objective

Malignant struma ovarii (SO) is a rare condition. Although there have been a few reported cases of malignant SO with coexisting Graves’ disease (GD), the exact incidence of metastasis in these cases is not known. We report a rare case of metastatic malignant SO coexisting with GD.

Methods

Clinical examination, pelvic ultrasound, and histopathology of the resected tumor were performed, followed by iodine-131 (I-131) and whole body scan. Antithyroglobulin titers were postoperatively followed.

Results

A 43-year-old woman with a history of left ovarian cystic teratoma with SO resected 8 years ago and recently diagnosed GD presented with lower abdominal fullness. Pelvis ultrasound showed a 13.8-cm left adnexal mass, and she underwent left salpingo- oophorectomy. Histology confirmed an intraovarian thyroid tissue housing a highly differentiated follicular thyroid carcinoma, with metastatic peritoneal deposits. She underwent completion surgery and total thyroidectomy. Histology showed no evidence of intrathyroidal malignancy. I-131 therapy was administered, and posttherapeutic I-131 whole body scan revealed a remnant disease. She was started on suppressive levothyroxine therapy and remained clinically well at her 1-year follow-up with downtrending antithyroglobulin titers.

Conclusion

The coexistence of malignant SO and GD is very rare, and even rarer is the coexistence of metastasis malignant SO and GD. To the best of our knowledge, this is the first reported case of metastatic malignant SO in the setting of GD.

Malignant struma ovarii: next-generation sequencing of six cases revealed Nras, Braf, and Jak3 mutations

PURPOSE

Struma ovarii (SO) is a highly specialized ovarian teratoma, consisting of thyroid tissue. Rarely, carcinomas histologically identical to their thyroid counterparts may occur, and are comprehensively defined as malignant struma ovarii (MSO). Their optimal management is controversial, and the molecular profile of the malignant counterpart in the ovary is incompletely known. In this study, the clinicopathological and molecular features of six MSO from different Italian Institutions were analysed, to explore genetic profiles of potential therapeutic interest.

METHODS

The histopathological features and immunoprofile (according to the known markers Galectin-3, HBME1, cytokeratin 19 and CD56) were reviewed. In addition, all cases underwent genetic analysis with a next-generation sequencing (NGS) hot spot cancer panel detecting mutations in 50 genes involved in cancerogenesis. RET/PTC rearrangements and TERT promoter alterations were also evaluated.

RESULTS

Papillary carcinoma in all similar to its thyroid counterpart was found in five of six cases, including classical (two tumors) and follicular variant (three tumors) types. The last case was a poorly differentiated carcinoma. An activating gene mutation, was detected in five of six cases, including two NRAS, two BRAF, and one JAK3 oncogene mutations. No alterations were found in the other panel genes, nor in TERT promoter, or in RET chromosomal regions.

CONCLUSIONS

MSO is a rare condition. Papillary carcinoma is the predominant malignant type, sharing both histomorphological and molecular features of its thyroid counterpart. Interestingly, the single case of poorly differentiated carcinoma displayed a JAK3 mutation. The presence of such driving mutation could be of potential interest in guiding postoperative treatment.

FIGO Stage IV and Age Over 55 Years as Prognostic Predicators in Patients With Metastatic Malignant Struma Ovarii

Introduction: Metastatic malignant struma ovarii (MSO) is an extremely rare disease that lacks treatment consensus and accurate prognosis. The objective of this study was to present the clinical, pathological, and treatment characteristics of metastatic MSO, while also investigate the overall survival (OS) rate and factors affecting prognosis in this population.

Materials and Methods: A total of 79 cases of metastatic MSO were reviewed, including four cases of metastatic MSO from our hospital and 75 cases selected from the literature. Logistic regression was used to identify potential factors affecting disease free survival (DFS). The Kaplan-Meier method and log-rank test were used to determine OS; further Cox regression was used to evaluate factors affecting OS.

Results: The mean age of all the patients at diagnosis was 43.8 years. The most common metastatic sites were peritoneum, bone, liver, omentum and lung in descending order. Only two patients (2.6%) coexisted with local primary thyroid cancer. Follicular carcinoma (41.8%) as the most prevalent subtype, followed by papillary carcinoma, follicular variant of papillary carcinoma, and mixed follicular-papillary carcinoma. 36.7% of the patients received conservative surgery, 43.0% of them underwent aggressive surgery, and 15.2% of them did not receive any surgery. 74.7% of patients who received adjuvant therapy underwent radioiodine therapy (RAI). Logistics regression revealed that FIGO stage IV was the only prognostic factor in predicting DFS (P = 0.002; Odds Ratio [OR] 5.333; 95% confidence interval [CI]: 1.839–15.471). Only seven deaths occurred. The OS rates at 5, 10, 15 years were 89.3, 82.4, 65.9%, respectively. Multivariate analysis showed age over 55 years (P = 0.006; OR 9.362; 95%CI: 1.895–46.246) was the only risk factor for OS.

Conclusion: Patients with metastatic MSO have an excellent disease-specific OS rate, FIGO stage IV and age over 55 years were two factors affecting disease prognosis. Conservative surgery with residual ablation by RAI after total thyroidectomy should be preferred since the benefits of aggressive surgery are uncertain.

Papillary thyroid carcinoma in Struma Ovarii

Struma Ovarii is one of the types of mature teratoma, with predominant thyroid tissue (>50%). It occurs in 1% of all cases of ovarian tumors and in 2.7% of dermoid tumors. There are no specific clinical, radiological or serum markers for this rare pathology. Rarely it may be accompanied by ascites and the increased level of CA-125. In general Stuma Ovarii is clinically defined as an ovarian malignancy. It is diagnosed only by histopathological examination of the surgical material. Diagnosis of Struma Ovarii dictates the need for advanced research of the thyroid. Struma Ovarii is mostly benign. Its malignant transformation occurs in only 5% of all cases, That leads to further management planning analogous to the treatment of thyroid cancer. The case of malignant Struma Ovarii of the 50-year-old woman, which led to total thyroidectomy and radioactive iodine therapy - is described.

Ovarian germ cell tumour classification: views from the testis

The classification of ovarian germ cell tumours has remained unchanged for many years, while there have been considerable changes in the testicular classification. In recent years there has been concern about the overtreatment of clinical stage 1 testicular germ cell tumours with increasing use of surveillance for low-risk disease. We outline here the current classification of germ cell tumours of the ovary with particular regard to treatment and outcome and highlight some areas which may cause confusion, particularly pertaining to immature teratomas and mixed germ cell tumours. We suggest that some minor changes to the classification, evidenced by a recent retrospective series by some of the authors, may lead to less adjuvant chemotherapy for immature teratomas and may obviate the need for the grading of immature teratomas, by aligning with testicular experience in pure post-pubertal teratomas. Adoption of this will require retrospective and prospective re-evaluation, but may avoid long-term patient morbidity.

Malignant Thyroid-type Papillary Neoplasm in Struma Ovarii: A Case Report

Papillary thyroid carcinoma (PTC) arising in a coexistent struma ovarii (SO) is a rare malignancy. It manifests with abdominal symptoms such as palpable mass, pain, distension, and possibly ascites. It is usually diagnosed postoperatively, and its histopathological diagnostic criteria remain identical to that of papillary carcinoma of the thyroid gland. Due to the relative rarity of the disease, definitive guidelines for its overall management are still undefined. We present a case of a 51-year old female with suspicion of a left ovarian tumor due to her presenting symptoms: raised serum CA-125 levels and abnormal abdominopelvic CT scan findings. She underwent complete surgical debulking of the mass (total abdominal hysterectomy (TAH), bilateral salpingo-oophorectomy (BSO), omentectomy, appendectomy, and pelvic lymphadenectomy). The mass was postoperatively diagnosed by histopathology as PTC in SO (stage IA). Furthermore, our patient did not receive any adjuvant treatment. The patient has been disease-free for 24 months post-surgery and is scheduled for regular biannual follow-ups.

Whole-Genome and Segmental Homozygosity Confirm Errors in Meiosis as Etiology of Struma Ovarii

Strumae ovarii are neoplasms composed of normal-appearing thyroid tissue that occur within the ovary and rarely spread to extraovarian sites. A unique case of struma ovarii with widespread dissemination detected 48 years after removal of a pelvic dermoid provided the opportunity to reexamine the molecular nature of this form of neoplasm. One tumor, from the heart, consisting of benign thyroid tissue was found to have whole-genome homozygosity. Another tumor from the right mandible composed of malignant-appearing thyroid tissue showed whole-genome homozygosity and a deletion of 7p, presumably the second hit that transformed it into a cancerous tumor. Specimens from 2 other cases of extraovarian struma confined to the abdomen and 8 of 9 cases of intraovarian struma showed genome-wide segmental homozygosity. These findings confirm errors in meiosis as the origin of struma ovarii. The histological and molecular findings further demonstrate that even when outside the ovary, strumae ovarii can behave nonaggressively until they receive a second hit, thereafter behaving like cancer.

Germ Cell Tumors of the Female Genital Tract

Ovarian germ cell tumors are a histologically diverse group of neoplasms with a common origin in the primitive germ cell. The vast majority are represented by mature cystic teratoma. In the minority are malignant germ cell tumors including immature teratoma, dysgerminoma, yolk sac tumor, embryonal cell carcinoma, and choriocarcinoma. This article reviews the histologic and immunohistochemical features of the most common ovarian germ cell tumors. The differential diagnoses for each are discussed.

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.

An unusual presentation of a papillary thyroid carcinoma in the struma ovarii in a 10 year-old girl: A case report

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Struma ovarii is an ovarian tumor with thyroid tissue as its predominant component.

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Most patients are euthyroid, but some reports have noted thyrotoxicosis originating from the malignant struma ovarii.

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Papillary thyroid carcinoma was reported as the soul mass of struma ovarii in our patient.

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Struma ovarii should be a possible diagnosis in female patients with thyrotoxicosis manifestations with normal thyroid scan and examination.

Introduction

Struma ovarii is an ovarian tumor with thyroid tissue as its predominant component. It usually occurs in older women and presents with abdominal mass, pain and abnormal bleeding. Most patients are euthyroid, but some reports have noted thyrotoxicosis originating from the malignant struma ovarii.

Presentation of case

A 10 year-old girl presented with tachycardia, normal thyroid exam and thyrotoxicosis. Thyroid scan showed no uptake with increased uptake in right ovary indicative of struma ovarii. The patient underwent oophorectomy and thyroidectomy, Pathology showed papillary thyroid carcinoma limited to the struma ovarii. Following TSH suppressive therapy and treatment with I¹³¹, she is totally symptom free.

Discussion

Struma ovarii should be a possible diagnosis in any female patient with thyrotoxicosis manifestations with normal thyroid scan and examination.

The largest reported papillary thyroid carcinoma arising in struma ovarii and metastasis to opposite ovary: case report and review of literature

Background

Malignant struma ovarii (MSO) is a very rare, germ cell tumor of the ovary, histologically identical to differentiated thyroid cancers. Struma ovarii (SO) is difficult to diagnose on clinical basis or imaging and is mostly discovered incidentally, with few published cases in the literature.

Case presentation

A 42-year old primiparous woman presented with abdominal pain and midline pelvic palpable firm mass arising from the pelvis. Imaging showed pelvic solid cystic mass. Total abdominal hysterectomy, bilateral salpingo-oopherectomy (TAH BSO) and infracolic omentectomy were performed. Histopathology revealed left ovary papillary thyroid carcinoma (PTC) arising in SO (11 cm) and metastatic papillary thyroid carcinoma in the right ovary. Thyroid functions tests were all normal, ultrasound thyroid showed two complex nodules in the left thyroid lobe. Total thyroidectomy was decided, but the patient refused further surgical management and was lost to follow up as she left the country. We undertook a comprehensive literature search, and MSO and thyroid management data from 23 additional publications were analyzed and tabulated. This PTC MSO is probably the largest reported in the literature.

Conclusions

Among the different surgeries for MSO, TAH + BSO appears to have the best clinical outcome. However, unilateral salpingo-oopherectomy/ unilateral oophorectomy and bilateral salpingo-oopherectomy also seem effective. Ovarian cystectomy alone seems associated with higher recurrence. There remains no consensus on the associations between MSO tumor size and potential extent of metastasis, and about the management of thyroid gland. However, surveillance and thyroid gland work up to detect concurrent thyroid cancer are recommended.

Rare Clinical Entity: Metastatic malignant struma ovarii diagnosed during pregnancy - Lessons for management

Background

Malignant struma ovarii is an ovarian teratoma containing at least 50% thyroid tissue which has the potential to metastasize and produce thyroid hormone. Given its rarity, management strategies are not well-established. We report a case of metastatic malignant struma ovarii discovered during pregnancy with lessons for evaluation and management.

Case presentation

A 30-year-old woman who was two months pregnant was discovered to have struma ovarii with over half of the struma comprised of papillary thyroid cancer. Following tumor resection, delivery, and thyroidectomy, she underwent evaluation with stimulated thyroglobulin testing and diagnostic staging sodium iodide-131 scan (I-131), which revealed the presence of skeletal metastases. Following administration of 320 mCi I-131, post-therapy scan also showed miliary pulmonary metastases with improved ability to localize the bony and pulmonary metastases with concurrent SPECT/CT imaging. A second dosimetry-guided I-131 therapy resulted in complete resolution of pulmonary metastases; however, small foci of residual bone disease persisted. Post-therapy scans demonstrated additional findings not shown on diagnostic I-131 scans obtained prior to both her initial and second I-131 therapy.

Conclusions

SPECT/CT provides accurate anatomic correlation and localization of metastatic foci and can serve as a baseline study to assess interval response to treatment. Post-therapy scans should always be obtained when I-131 treatment is administered, as additional findings may be revealed versus low dose I-131 activity diagnostic scans. This patient had a high metastatic burden that would not have been discovered in a timely fashion with the conservative approach advocated by others. Thyroidectomy followed by a diagnostic staging radioiodine scan and a stimulated thyroglobulin level should be considered in patients with malignant struma ovarii for guiding therapeutic I-131 administration as metastatic risk is difficult to predict based on histopathologic examination.