Metastasis to the thyroid gland: a single-institution 16-year experience

Ultrasonographic features and diagnostic accuracy of FNA and CNB in secondary thyroid malignancies: A retrospective study

Objective

This study aims to examine the ultrasonographic features of secondary thyroid malignancies and compare the diagnostic efficacy of fine-needle aspiration (FNA) and core needle biopsy (CNB) in this condition.

Methods

A retrospective analysis was conducted on 29 patients with secondary thyroid malignancies treated at our center between July 2011 and October 2022. Ultrasound images and clinical data were analyzed, and the lesions were classified according to the American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS).

Results

Among the 29 patients studied, primary tumor sites were predominantly the esophagus, lung, and nasopharynx. Comprehensive ultrasound data was available for 28 of these patients, revealing nodular lesions in 24 cases and diffuse lesions in 4 cases. Nodular lesions were predominantly solid or nearly solid hypoechoic nodules with parallel growth and extrathyroidal extension features, with a few showing macrocalcifications. Most patients had varying degrees of metastasis to neck lymph nodes. FNA accurately diagnosed 31.6 % of the lesions as secondary thyroid malignancies, while 5.3 % were misdiagnosed as papillary thyroid carcinoma (PTC). However, CNB demonstrated 100 % reliability in diagnosing secondary thyroid malignancies.

Conclusion

This study's categorization of secondary thyroid malignancy ultrasonographic features identifies nodular and diffuse patterns, with the application of ACR TI-RADS proving effective for nodular types. In detecting these lesions, CNB demonstrates superior sensitivity compared to FNA. Thus, in cases of thyroid lesions suspected to be malignant, particularly with enlarged neck lymph nodes and in patients with a history of malignancy, CNB is recommended as the diagnostic method of choice.

Use of PSMA PET/CT to detect prostate cancer metastatic to a preexisting thyroid nodule

Prostate cancer (PCa) seldom metastasizes to the thyroid gland, and only a limited number of cases are documented in the literature. The application of a relatively recent and highly sensitive imaging technique, prostate-specific membrane antigen (PSMA) positron emission tomography-computed tomography (PET/CT), has enhanced the identification of metastatic disease. Nevertheless, as PSMA is expressed in various tissue types, the clinical importance of a PSMA-avid thyroid lesion remains largely uncertain. A minor, yet noteworthy, percentage of these lesions are ultimately determined to be malignant. Here we describe the case of a 70-year-old man with a past medical history of Lynch syndrome who presented to an outpatient oncologic clinic for management of very high risk localized PCa. He developed metastatic recurrence and his disease progressed through several lines of therapy, including immunotherapy and targeted treatments. He was found to have a new, intense PSMA uptake in an existing, previously benign thyroid nodule. Sonographic evaluation revealed changing morphology despite grossly stable size. Repeat biopsy confirmed the unusual finding of PCa metastasis to a known thyroid nodule. The shift in PSMA avidity played a pivotal role in discerning this metastatic deposit. There is a potential risk that such lesions may be inadequately acknowledged. The impact of the patient's Lynch syndrome on this presentation remains uncertain.

Fine-needle aspiration diagnosis of secondary malignant tumors of the thyroid gland: A single-institution experience of 17 cases

BACKGROUND

Fine-needle aspiration (FNA) is the most commonly used preoperative pathological diagnostic tool for thyroid tumors. Secondary malignant tumors of the thyroid gland account for less than 3% of all thyroid malignancies. The aim of this study was to investigate the types and cytopathological features of secondary thyroid tumors, evaluate diagnostic pitfalls in FNA.

METHODS

Cases of secondary thyroid tumors diagnosed in the Department of Pathology of Shaanxi Provincial People's Hospital were collected, and their clinical data, cytologic features, immunohistochemical results, and histopathological diagnoses were summarized.

RESULTS

The study included 17 cases (8 males and 9 females) with a mean age of 60.4 ± 9.4 years (range, 45-83 years). Six cases had a known history of primary malignancy prior to FNA aspiration diagnosis. The most common organs of origin were the lungs (5 cases, 3 adenocarcinoma, and 2 small-cell carcinoma) and esophagus (5 cases, 3 squamous-cell carcinoma, 1 adenocarcinoma, and 1 small-cell carcinoma). The next most common was squamous-cell carcinoma of the larynx (3 cases), and gastric tumor (2 cases), including 1 lymphoma and 1 adenocarcinoma. Cell blocks and immunohistochemistry were performed in 12 of these cases. Comparison of the impact of positive history and IHC availability on the accuracy of pathologic diagnosis showed that both were statistically significant.

CONCLUSION

FNA is an effective means of diagnosing secondary malignancies of the thyroid, in which knowledge of the patient's history of malignancy is essential, and the use of cell blocks and immunohistochemistry helps to clarify the pathological diagnosis.

Pink-on-pink: hepatocellular carcinoma metastatic to oncocytic carcinoma of the thyroid

Hepatocellular carcinoma typically metastasizes within the liver and may involve extrahepatic sites such as the lungs, adrenal glands, and bones at advanced stages. However, hepatocellular carcinoma metastasis to the thyroid is very uncommon and tumor-to-tumor metastasis from a hepatocellular cancer to a thyroid neoplasm is extremely rare. In this report, we present a case of a 70-year-old man with a hepatocellular carcinoma metastasizing to oncocytic thyroid carcinoma, emphasizing the importance of clinical history and of a multidisciplinary approach, as well as the usefulness of site-specific immunohistochemical markers, in diagnosing and managing cases of Rosai's metastasis, especially when donor and recipient neoplasms share similar histologic features.

Thyroid gland: a rare site of metastasis

PURPOSE

Despite its rich vascularity, metastasis (MTS) to the thyroid tissue is unusual, ranging from 1 to 3%. This entity is not usually considered as differential diagnosis and is not included in the upfront approach in patients with thyroid nodules. Once diagnosed, treatment is controversial. The aim of this study was to evaluate diagnosis, treatment, and outcome at the end of follow-up in patients with a diagnosis of MTS to the thyroid.

METHODS

A retrospective multicenter study was designed from 1985 to 2022; 29 patients with MTS to the thyroid gland were included in the analysis.

RESULTS

Clinical presentation included the presence of a nodular goiter (65.5%), compression symptoms (17.2%), diffuse goiter (10.3%), and suspicious lymph nodes in the neck (7%). Primary tumor sites were: kidney (44.8%), breast (24.1%), lung (13.8%), neuroendocrine system (6.9%), colon (3.4%), cervix (3.4%), and ovary (3.4%). In 18/23 patients, suspicious ultrasound criteria for malignancy were described. Preoperative diagnosis was made in 23/27 patients by FNA and confirmed in 18 cases by immunohistochemistry. Seventeen patients underwent surgery. At the end of the follow-up, 19 patients had died of oncological disease, and six were alive (2/6 disease-free with isolated intrathyroidal MTS).

CONCLUSION

Renal carcinoma was the tumor that most frequently metastasized to the thyroid gland. Immunodiagnosis was a very useful tool for etiological confirmation. Patients with MTS to the thyroid gland as a unique site had a more favorable course compared to patients with multiple metastatic sites. Finally, outcomes and prognosis essentially depended on the biology of the primary tumor.

Outcomes of thyroidectomy for secondary thyroid malignancies, a single center experience

BACKGROUND

Metastasis of primary malignancies of other organs to the thyroid gland is a rare condition that may pose a diagnostic challenge. In this study, we aimed to report the clinicopathologic features and outcomes of patients treated for secondary thyroid malignancies in our center.

MATERIALS AND METHODS

The results of patients who underwent thyroidectomy in our clinic between 2015 and 2023 were evaluated retrospectively. Four patients who met the inclusion criteria were evaluated.

RESULTS

The primary tumor was renal cell carcinoma in 2 patients and squamous cell carcinoma of the lung in 2 patients. Median age was 64 years (min:59-max:69). The median nodule diameter was 2.85 cm. Extrathyroidal spread was present in 1 patient with renal cell carcinoma metastasis. The other patient with renal cell carcinoma metastasis had lymphatic invasion. Vascular invasion was detected in 1 patient with renal cell carcinoma metastasis and 1 patient with squamous cell carcinoma of the lung metastasis. Surgical margin positivity was present in 1 patient in each group. The median overall survival time was 27 (min:10-max:44) months in the renal cell carcinoma group and 11 (min:6-max:16) months in the squamous cell carcinoma group. After the diagnosis of primary renal cell carcinoma, one patient metastasized to thyroid tissue 43.00 and one patient 94.00 months later. In the squamous cell carcinoma group, one patient showed metastasis to thyroid tissue 6.00 months after the primary diagnosis, while the other patient was first diagnosed with metastatic tissue.

CONCLUSIONS

Metastasis to the thyroid gland is a rare phenomenon with an incidence of 0.22% in all thyroid malignancies. It may occur before the detection of the primary tumor or during the follow-up of the primary malignancy. Although the overall prognosis is poor, it can be treated surgically.

Papillary thyroid carcinoma with clear cell renal cell carcinoma metastasized to the thyroid gland: A case report

Metastasis of clear cell renal cell carcinoma (ccRCC) to the thyroid gland is rare, and simultaneous occurrence of ccRCC and papillary thyroid carcinoma (PTC) is even rarer. Due to the occult nature of the disease, the clinical diagnosis is difficult. In the case of multiple tumors, the possibility of thyroid metastasis should not be ignored during the clinical diagnosis and treatment of PTC. The present study reported a case with initial diagnosis of PTC and accidental discovery of thyroid metastasis of ccRCC. This case study aims to improve the understanding of occult thyroid metastasis, providing a reference for its clinical diagnosis and treatment. Accordingly, misdiagnosis and missed diagnosis of this disease may be reduced and the survival rate and the life quality of patients can be improved.

Tumor-to-tumor spread: a case report and literature review of renal cell carcinoma metastasis into thyroid cancer

Tumor-to-tumor metastasis is a rare, yet important entity. Patients with a history of renal cell carcinoma (RCC) may have tumor deposits to the thyroid gland preceding or following their initial cancer diagnosis for many years. The diagnosis can be challenging, and clinicians must remain suspicious of a newly found thyroid nodule in a patient with a history of RCC. In this review, we report a case of a patient with RCC who was incidentally found to have a thyroid nodule on surveillance imaging found to be consistent with tumor-to-tumor metastasis from RCC into papillary thyroid carcinoma. It is imperative to consider this diagnosis as the thyroid is the most common site of spread, and treatment with partial or total thyroidectomy has led to improved survival.

Positive Delphian node in laryngeal cancer: Predictive of thyroid gland metastasis?

INTRODUCTION

Laryngeal carcinoma represents the 22nd most common cancer worldwide. Thyroid metastasis from laryngeal cancer is extremely rare. Overall, thyroid gland involvement by metastatic carcinoma represents about 1.1-2.1 % among thyroid malignant diseases.

PRESENTATION OF CASE

A male in his 70s came to our Otolaryngology Unit with a laryngeal squamous cell carcinoma (cT3). Total laryngectomy and bilateral neck dissection were performed. Histological examination revealed a pT3 carcinoma with sub-massive metastasis of the Delphian node. The patient underwent close follow-up. After eight months, neck examination revealed a suspected nodule in the right thyroid lobe. A right thyroid lobectomy was performed, and histological assessment revealed a nodule with squamous carcinoma metastasis in the superior pole of the thyroid lobe. The remaining thyroid tissue was affected by multinodular macrofollicular goitre. The patient underwent adjuvant therapy. One year after the second surgery, he showed no signs of recurrence.

DISCUSSION

Thyroid gland metastasis from laryngeal carcinoma is a very rare occurrence. In literature, we found only three articles that describes thyroid metastasis in overall 7 patients affected by laryngeal squamous cell carcinoma. Positive Delphian lymph node is usually related to poor prognosis: in 2007 a study reported tumour recurrence in 15 out of 25 patients with metastatic Delphian lymph node within the first two years of surgery.

CONCLUSION

Thyroid gland metastasis from laryngeal carcinoma is rare; so close follow-up of oncologic patients is mandatory and, most of all, the positive Delphian node should not be underestimated for its predictive value.

Ultrasonographic Findings and Prognosis of Metastases to the Thyroid Gland

Metastases to the thyroid gland (MTT) are uncommon in clinical practice. The ultrasound (US) features are easily confused with primary thyroid malignancy, Hashimoto's thyroiditis, and other thyroid diseases. Therefore, this study aimed to assess the role of US and analysis of prognosis of MTT. A total of 45 patients with MTT in the database between July 2009 and February 2022 at the Fujian Cancer Hospital were reviewed. US examinations were performed only on 20 patients, who were finally included in our study. Among the 20 patients, nine were male, and eleven were female. According to US characteristics, metastases to the thyroid gland were divided into nodular and diffuse types (17 and 3 cases, respectively). Three lesions (17.6%) had circumscribed margins, and 14 (82.4%) were uncircumscribed. Three lesions (17.6%) were regular in shape, and 14 (82.4%) were irregular. Nine metastases (52.9%) were a taller-than-wide shape, and eight (47.1%) were not a taller-than-wide shape. Ten lesions (58.8%) had rich vascularity, and seven (41.2%) had absence/not rich vascularity. The mean overall survival (OS) from the time of MTT diagnosis was 22 months (95% confidence interval: 5.95-38.05). The 1-, 3-, and 5-year OS after metastasis was 68.1%, 25.5%, and 17%, respectively. The prognosis of MTT was poor, which is closely related to the characteristics of the primary tumor and metastatic disease. The US findings and US-guided core needle biopsy may be useful in diagnosing MTT in patients with a history of the malignant tumors.

Clinical, cytological, and pathological characteristics of metastatic renal cell carcinoma to the thyroid: A study of 14 cases at a Japanese single institution

A preoperative diagnosis of metastatic renal cell carcinoma to the thyroid (MRCCT) is important for determining clinical management but is challenging even in cases with a clinical history of renal cell carcinoma (RCC). This study aimed to elucidate the clinical, cytological, and pathological characteristics of MRCCT. Fourteen MRCCT cases extracted from 18 320 malignant thyroid tumors were included in this study. Twelve MRCCT (85.7%) occurred as solitary lesions and the most frequently suspected lesions on ultrasonography were follicular tumors. On cytology, 46.2% of cases were reported as RCC or suspected RCC; a medical history of RCC and immunocytochemistry were helpful in interpretation. RCC metastasized to a follicular adenoma in 50.0% of the solitary lesions. MRCCTs with a long interval from the initial presentation, solitary lesion, and Ki-67 labeling index <10% showed significantly longer disease-free survival. MRCCT is characterized by a long interval from the initial presentation of RCC, appearance as a solitary nodule, ultrasonographic similarity to follicular tumors, sharing cytological findings with primary thyroid tumors, and high frequency of metastasis within follicular adenoma. A long interval from the initial presentation, occurrence as a solitary lesion, and low Ki-67 labeling index may be favorable prognostic factors.

Fast Track Management of Primary Thyroid Lymphoma in the Very Elderly Patient

A rapid growing cervical mass mobile while swallowing is the most common clinical presentation of severe thyroid malignancy. A 91-year-old female patient with a history of Hashimoto thyroiditis presented with clinical compressive neck symptoms. The patient had gastric Maltoma diagnosed that was surgically resected thirty years ago. A straightforward process was needed to reach full histological diagnosis and initiate prompt therapy. Ultrasound (US) showed a 67 mm hypoechoic left thyroid mass with reticulated pattern without signs of locoregional invasion. Percutaneous trans isthmic US-guided 18G core needle biopsy (CNB) disclosed diffuse large B cell lymphoma of the thyroid gland. FDG PET revealed two distinct thyroid and gastric foci (both SUVmax 39.1). Therapy was initiated rapidly to decrease clinical symptoms in this aggressive stage III primitive malignant thyroid lymphoma. The prognostic nomogram was calculated by using a seven-item scale, which disclosed a one-year overall survival rate of 52%. The patient underwent three R-CVP chemotherapy courses, then refused further treatment and died within five months. Real-time US-guided CNB approach led to rapid patient's management that was tailored to patient's characteristics. Transformation of Maltoma into diffuse large B cell lymphoma (DLBCL) into two body areas is deemed to be extremely rare.

Intratumoural metastasis of primary lung adenocarcinoma to non-invasive follicular thyroid neoplasm with papillary-like nuclear features

Metastasis to the thyroid gland is very uncommon with an incidence of 2-3% of all thyroid malignancies. A higher incidence is noted in autopsy studies indicating incidental detection. However, tumour-to-tumour metastasis is extremely uncommon with a handful of cases published in the literature to date. Also, non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFT-P) is a rare neoplasm; diagnosis requires meticulous sampling of the entire capsule and fulfilment of other diagnostic criteria. We report a case of primary adenocarcinoma of lung in a 57-year-old female who additionally had a left thyroid nodule which appeared suspicious on ultrasonography. Histology of lung tumour was conventional papillary adenocarcinoma while aspiration cytology from the thyroid raised suspicion of metastatic adenocarcinoma. On hemithyroidectomy, the thyroid nodule showed metastatic adenocarcinoma in the centre of the nodule, while the peripheral portion showed non-invasive follicular thyroid neoplasm with papillary-like nuclear features; the diagnosis of which was confirmed with complete sampling of the thyroid capsule. The immunoprofile also supported the above dual histology. This is an extremely uncommon occurrence and metastasis within a NIFT-P has not been reported to the best of our knowledge.

Metastatic renal cell carcinoma to the thyroid with cervicothoracic venous tumor thrombosis

INTRODUCTION

Metastatic renal cell carcinoma (RCC) represents 25%-42% of metastatic thyroid malignancies. Propensity for RCC to demonstrate intravascular extension to the inferior vena cava is well documented. We present an analogous phenomenon of intravascular extension to the internal jugular vein (IJV) from thyroid gland metastasis.

METHODS

A 69-year-old male presented with metastatic RCC of the right thyroid lobe. Imaging demonstrated tumor thrombosis of the ipsilateral IJV, extending inferiorly to the junction of the brachiocephalic, subclavian, and internal jugular veins within the mediastinum.

RESULTS

Surgical excision required control of both the IJV in the neck and mediastinal venous great vessels via sternotomy, prior to subtotal thyroidectomy and venotomy for en bloc resection.

CONCLUSION

This case report describes metastatic RCC to the thyroid gland with cervicothoracic venous tumor thrombosis successfully treated with subtotal thyroidectomy, sternotomy for venotomy and tumor thrombectomy, and preservation of IJV conduit.

Top 10 Clear Cell Head and Neck Lesions to Contemplate

BACKGROUND

Optically clear cytoplasm may occur in neoplastic and non-neoplastic conditions, either as a characteristic feature of a disease entity or as a morphologic rarity, potentially creating diagnostic dilemmas in various organ systems. In the head and neck, clear cell change can occur in lesions of salivary, odontogenic, thyroid, parathyroid, or sinonasal/skull base origin, as well as in metastases to these regions.

METHODS

This review elaborates the top ten clear cell lesions in the head and neck, emphasizing their distinguishing histologic, immunohistochemical, and molecular attributes, and presents a rational approach to arriving at an accurate classification.

RESULTS

Cytoplasmic pallor or clearing may be caused by accumulations of glycogen, lipid, mucin, mucopolysaccharides, water, foreign material, hydropic organelles, or immature zymogen granules. Overlapping morphologic features may present a diagnostic challenge to the surgical pathologist. Similarity in immunohistochemical profiles, often due to common cell type, as well as rare non-neoplastic mimics, furthers the diagnostic conundrum.

CONCLUSIONS

The top ten lesions reviewed in this article are as follows: (1) clear cell carcinoma (salivary and odontogenic), (2) mucoepidermoid carcinoma, (3) myoepithelial and epithelial-myoepithelial carcinoma, (4) oncocytic salivary gland lesions, (5) squamous cell carcinoma, (6) parathyroid water clear cell adenoma, (7) metastatic renal cell carcinoma (especially in comparison to clear cell thyroid neoplasms), (8) sinonasal renal cell-like adenocarcinoma, (9) chordoma, and (10) rhinoscleroma.

Neuroendocrine neoplasm with metastasis to the thyroid: a case report and literature review

Thyroid cancer can be divided into two types according to its cellular origin, i.e., malignant tumors originating from thyroid cells and cancers that metastasize to the thyroid from other sites, the latter of which are, clinically rare. This article reports the diagnosis and treatment of a rectal neuroendocrine neoplasm metastasis to the thyroid. No similar cases have been reported before. This case suggests that when evaluating thyroid tumors, clinicians should not only carefully identify the clinical features of the tumor but also pay special attention to the patient's history of tumors, especially neuroendocrine neoplasms. For definite secondary thyroid malignancies, neck surgery is feasible if the thyroid is the only site of metastasis; otherwise, the subsequent diagnosis and treatment plan should be determined after a comprehensive evaluation of the primary tumor and patient's general condition.

Advances in Thyroid Pathology: High Grade Follicular Cell-derived Thyroid Carcinoma and Anaplastic Thyroid Carcinoma

In the upcoming World Health Organization fifth edition classification of endocrine tumors, there were several major changes related to high grade follicular-derived thyroid carcinoma (HGFCTC) and anaplastic thyroid carcinoma (ATC) based on emerging evidence about the diagnostic criteria clinical behavior, prognostic factors, and molecular signatures of these tumors. In this review, we aim to summarize the major evolutions of HGFCTC and ATC. HGFCTC is a nonanaplastic carcinoma with high grade features (High mitotic count, tumor necrosis). It is subdivided into poorly differentiated thyroid carcinoma diagnosed using the Turin proposal and differentiated high grade thyroid carcinoma. The latter is defined by the presence of the cytoarchitectutal features of well-differentiated thyroid carcinoma (eg, papillae) but harbors elevated mitotic activity and/or tumor necrosis. Poorly differentiated thyroid carcinoma is predominantly RAS -driven and associated with RAI avidity and high propensity for distant metastasis, whereas differentiated high grade thyroid carcinoma is mostly BRAFV600E -driven. ATC may show a wide range of histologic features. Carcinoma of pure squamous phenotype is associated with a high frequency of BRAF V600E mutations and is now considered as a subtype of ATC. There is a stepwise molecular progression from well-differentiated carcinoma to HGFCTC to ATC manifested by 1) early and persistent driver alteration in the MAPK pathway, particularly BRAF V600E and RAS mutations, and 2) gain of secondary aggressive molecular signatures (such as TERT promoter and TP53 mutations) when tumors progress from well-differentiated to high grade to anaplastic carcinoma.

Metastatic Clear Cell Renal Cell Carcinoma Involving the Thyroid Gland: A Clinicopathologic Study of 17 Patients

Background. Metastatic clear cell renal cell carcinoma (RCC) is one of the most common secondary thyroid malignancies. Diagnosis can be challenging, particularly if presenting many years after initial diagnosis. We reviewed clinicopathologic features and immunoprofile of metastatic clear cell RCC in thyroid. Design. We identified 17 patients from 2003-2021. Clinical data were obtained from medical records, and slides were retrieved and reviewed. Results. Seventeen patients (12 male and 5 female) included 12 thyroidectomies, 3 core biopsies, 1 excisional biopsy, and 1 fine-needle aspiration. The average patient age was 68.7 years (range, 45-88 years). Sixteen patients had history of clear cell RCC, and in 1 patient, the clear cell RCC was discovered after the thyroid metastasis was found. Thyroid gland metastases were on average diagnosed 90.7 months after the diagnosis of the renal primary (range, 24-240 months). Patients presented with a new palpable mass (n = 11) or dyspnea/stridor (n = 1). Five tumors were incidentally found via surveillance imaging. In 2 patients, metastases occurred within follicular thyroid neoplasms. All metastases showed conspicuous sinusoidal vasculature between the tumor nests and areas of myxoid degeneration. A prominent thick fibromuscular pseudocapsule was evident in 10 resections. Immunohistochemistry (n = 5) showed that the metastases were positive for PAX8, CA9, and CD10, while negative for keratin 7, thyroglobulin, and TTF1. Conclusions. Metastatic clear cell RCC involving the thyroid gland is infrequent and typically occurs remotely after the initial diagnosis. Cytologic and histologic features may show significant overlap with primary thyroid lesions. Immunohistochemistry can help reliably distinguish metastases from primary thyroid neoplasms.

[Analysis of Clinicopathological Characteristics of 88 Cases with Secondary Neoplasms of the Thyroid Gland]

Objective

To analyze the clinicopathological characteristics of secondary neoplasms of the thyroid gland (SNTGs).

Methods

SNTG Patients who had pathology diagnosis of SNTGs between January 2010 and December 2019 at West China Hospital, Sichuan University were retrospectively enrolled. The SNTG cases were divided into two groups, a local invasion group and a distant metastasis group, and their clinical features were reviewed.

Results

The study involved 88 patients, with a female-to-male (F/M) ratio of 1/3 and an average age of 56 years. The local invasion group consisted of 72 patients (F/M, 1/8) who had the following types of tumors: 65 had squamous cell carcinomas (45 originated from larynx and 10 from laryngopharynx), 4 had adenoid cystic carcinomas, 1 had neuroendocrine carcinoma of esophagus, 1 had giant cell tumor, and 1 had type B3 thymoma. The distant metastasis group consisted of 16 patients (F/M, 7/1), all with previously confirmed history of malignancies of sites distant from the thyroid. Their primary tumor types were as follows, 6 had breast carcinomas, 5 had lung adenocarcinomas, 2 had nasopharyngeal non-keratinizing carcinomas, 1 had clear cell renal carcinoma, 1 had colon adenocarcinoma, and 1 had cervical squamous cell carcinoma.

Conclusions

Given that SNTGs are generally rare, the local invasion cases were predominantly squamous cell carcinomas that mainly originated from the larynx and the patients usually had no previous history of malignancy, while the distant metastasis cases often had a corresponding history of malignancies, consisting mainly of breast carcinoma and lung carcinoma.

Metastases to the Thyroid Gland: What Can We Do?

Metastases to the thyroid gland arise from other malignant tumors such as renal cell carcinoma, colorectal cancer, lung cancer, and breast cancer. In clinical practice, the incidence is low, and the symptoms are not specific, so it is often missed and misdiagnosed. It is finally diagnosed via the comprehensive application of many diagnostic methods, such as ultrasound, fine-needle aspiration biopsy, and immunohistochemistry analysis. Surgery-based comprehensive treatment is often adopted, but because it is usually in the late stage of the primary tumor, the prognosis is poor. In order to better understand the related characteristics of thyroid metastatic cancer and then improve the clinical diagnosis and treatment and the prognosis of patients, in this paper, we systematically summarize the research status of thyroid metastatic cancer.

Clinicopathological and Molecular Features of Secondary Cancer (Metastasis) to the Thyroid and Advances in Management

Secondary tumours to the thyroid gland are uncommon and often incidentally discovered on imaging. Symptomatic patients often present with a neck mass. Collision tumours of secondary tumours and primary thyroid neoplasms do occur. Ultrasound-guided fine-needle aspiration, core-needle biopsy, and surgical resection with histological and immunohistochemical analysis are employed to confirm diagnosis as well as for applying molecular studies to identify candidates for targeted therapy. Biopsy at the metastatic site can identify mutations (such as EGFR, K-Ras, VHL) and translocations (such as EML4-ALK fusion) important in planning target therapies. Patients with advanced-stage primary cancers, widespread dissemination, or unknown primary origin often have a poor prognosis. Those with isolated metastasis to the thyroid have better survival outcomes and are more likely to undergo thyroid resection. Systemic therapies, such as chemotherapy and hormonal therapy, are often used as adjuvant treatment post-operatively or in patients with disseminated disease. New targeted therapies, such as tyrosine kinase inhibitors and immune checkpoint inhibitors, have shown success in reported cases. A tailored treatment plan based on primary tumour features, overall cancer burden, and co-morbidities is imperative. To conclude, secondary cancer to the thyroid is uncommon, and awareness of the updates on diagnosis and management is needed.

Application of Immunohistochemistry in Papillary Thyroid Carcinoma

Immunohistochemistry (IHC) is an economic and precise method to localize the presence of specific protein at cellular level in tissue. Although many papillary thyroid carcinomas do not require IHC to render a diagnosis, there are certain scenarios in which IHC are important. The major diagnostic applications of IHC include confirmation of papillary thyroid carcinoma in sites other than the thyroid, distinguish papillary thyroid carcinoma from other primary thyroid neoplasms in thyroid, and identify papillary thyroid carcinoma from secondary tumors to the thyroid. At research level, IHC could help identify prognostic information, identify underlying genetic alterations, and predict response to treatment in papillary thyroid carcinoma. The understanding of principle and recent advances in IHC will improve the diagnosis and management of patients with thyroid lesions including papillary thyroid carcinoma.

Metastasis to the thyroid gland: Characterization and survival of an institutional series spanning 28 years

INTRODUCTION

Secondary neoplasms in the thyroid are rare. The study aim was to provide an overview of non-thyroid tumours that metastasize to the thyroid through our institutional experience.

MATERIALS AND METHODS

This study entailed a review of the pathology database searching for patients with metastasis to the thyroid at the Karolinska University Hospital between 1992 and 2019 and review of their medical files.

RESULTS

Out of 1939 surgical procedures with a histopathological diagnosis of a thyroid malignancy, 31 cases (1.6%, 65% females) with a diagnosis of metastatic epithelial neoplasms to the thyroid gland were identified. The median age at discovery of the thyroid metastasis was 68 years (range 48-85). The most common primary tumours were clear cell renal cell carcinoma (ccRCC) (36%), followed by non-small cell lung cancer (19%), oesophageal cancer (16%), head and neck malignancies (16%), malignant melanoma (10%) and unknown primary tumour (3%). The median time from the diagnosis of the primary tumour to diagnosis of the thyroid metastasis was 20 months (0-232) and was longest for patients with ccRCC (median 107 months). At 12 months after the non-thyroid metastasis diagnosis 48% had died. The longest survival was observed in ccRCC and the shortest in lung cancer. Surgical management of the metastasis was associated with improved survival (25 vs 3.8 months, p = 0.001).

CONCLUSIONS

Non-thyroid metastases to the thyroid were rare but should be suspected in patients with previous history of non-thyroid malignancy and a thyroid nodule. Prognosis was poor, but surgical management was beneficial in selected patients.