Ectopic thyroid in EBUS: experience from a quality assurance programme.

A diagnostic challenge is presented: Distinguishing ectopic thyroid tissue from metastatic well-differentiated follicular carcinoma in cytological material. Two cases of thyroid tissue in mediastinal lymph nodes were sampled by endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA). Later, the cases were presented in Labquality's nongynecological external quality scheme rounds in the years 2017, 2019, and 2020. The same case was presented two times, both in the 2017 and in the 2020 rounds. The results of the three rounds and the discussion of diagnostic pitfalls of ectopic thyroid tissue are presented. A total of 112 individual laboratories worldwide participated in the external quality assurance rounds with whole-slide scanned images and digital still images of alcohol-fixed Papanicolaou-stained cytospin specimens in the years 2017, 2019, and 2020. Fifty-three laboratories participated in both the 2017 (53 of 70, 75.71%) and the 2020 (53 of 85, 62.35%) rounds. The given Pap classes between rounds were compared. Twelve (12 of 53, 22.6%) of the laboratories gave the same Pap class value, whereas 32 (32 of 53, 60.4%) were in the range of ±1 class difference (Cohen's kappa -0.035, p < 0.637). When comparing the diagnoses, 21 (21 of 53, 39.6%) laboratories gave the same diagnosis in 2017 and in 2020 (Cohen's kappa 0.039, p < 0.625). Thirty-two of the laboratories gave the same diagnosis both in 2017 and in 2020 (Cohen's kappa 0.004, p < 0.979). Ten (10 of 53, 18.9%) laboratories changed their diagnose from malignant to benign, and 11 (11 of 53, 20.8%) changed their diagnose from benign to malignant between the 2017 and the 2020 rounds. In conclusions, the expert reference diagnosis was thyroid tissue in mediastinal lymph node. Thyroid tissue in mediastinal lymph node may be either of ectopic or of neoplastic origin. The diagnostic work-up should include cytomorphological, immunohistochemical, laboratory, and imaging results. If a neoplastic change is excluded, the benign category is the most feasible one. The quality assurance rounds showed a large variability in the given Pap classes. Mirroring the problematic issue both inter- and intralaboratory of such cases both in routine diagnostics and in the classification terminologies is requiring multidisciplinary evaluation approach in the diagnostics.

NKX2-5 Variant in Two Siblings with Thyroid Hemiagenesis.

Thyroid hemiagenesis (THA) is an inborn absence of one thyroid lobe of largely unknown etiopathogenesis. The aim of the study was to reveal genetic factors responsible for thyroid maldevelopment in two siblings with THA. None of the family members presented with congenital heart defect. The samples were subjected to whole-exome sequencing (WES) (Illumina, TruSeq Exome Enrichment Kit, San Diego, CA 92121, USA). An ultra-rare variant c.839C>T (p.Pro280Leu) in NKX2-5 gene (NM_004387.4) was identified in both affected children and an unaffected father. In the mother, the variant was not present. This variant is reported in population databases with 0.0000655 MAF (GnomAD v3, dbSNP rs761596254). The affected amino acid position is moderately conserved (positive scores in PhyloP: 1.364 and phastCons: 0.398). Functional prediction algorithms showed deleterious impact (dbNSFP v4.1, FATHMM, SIFT) or benign (CADD, PolyPhen-2, Mutation Assessor). According to ACMG criteria, variant is classified as having uncertain clinical significance. For the first time, NKX2-5 gene variants were found in two siblings with THA, providing evidence for its potential contribution to the pathogenesis of this type of thyroid dysgenesis. The presence of the variant in an unaffected parent, carrier of p.Pro280Leu variant, suggests potential contribution of yet unidentified additional factors determining the final penetrance and expression.

Ectopic thyroid in left parotid gland with an orthotopic thyroid gland: A rare case scenario.

Benign ectopic thyroid tissue within the parotid gland is very rare with only one case reported till date in the world literature. We report a case of ectopic thyroid in the left parotid gland with an orthotopic thyroid in an elderly female, who was presented to us with the simultaneous onset of right-sided thyroid swelling and left parotid swelling for 6 months. Fine-needle aspiration cytology (FNAC) was done from both the swellings and a diagnosis of Hurthle cell neoplasm metastasizing to the left parotid gland was initially made. However, histopathological examination along with the immunohistochemistry (IHC) panel proved it to be an ectopic thyroid in the parotid. The case is being documented here for its rarity as well as an unusual presentation so that the readers are aware of this entity and the complete workup required to prevent diagnostic pitfalls.

Thyroid tissue outside the thyroid gland: Differential diagnosis and associated diagnostic challenges.

The presence of thyroid tissue outside of the thyroid gland may occur in various clinical settings and anatomic locations and includes both benign and malignant differential diagnoses. Some of these entities include thyroglossal duct cyst, lingual thyroid, parasitic nodule, thyroid tissue within a lymph node and struma ovarii. In routine daily practice, these entities do pose diagnostic challenges for the pathologists. Differential diagnostic considerations depend largely on the location of lesion and the histologic features. A definitive diagnosis may remain unclear in some cases while knowledge is still evolving in others i.e., incidentally detected bland appearing thyroid follicles in a lateral neck lymph node. This article aims to elaborate on the various entities characterized by thyroid tissue outside of the thyroid gland, both benign and malignant, and the relevant differential diagnostic considerations.

Slc:Wistar/ST rats develop unilateral thyroid dysgenesis: A novel animal model of thyroid hemiagenesis.

Developmental anomalies of the thyroid gland lead to congenital malformations such as thyroglossal duct cysts and thyroid dysgenesis. However, the pathogenesis of thyroid dysgenesis remains unclear due to the lack of suitable animal models. This study demonstrated that Slc:Wistar/ST rats frequently developed unilateral thyroid dysgenesis, including hemiagenesis, characterized by the absence of one lobe. In Wistar/ST rats, each thyroid lobe was frequently different in size, and approximately 27% and 20% of the rats presented with hemihypoplasia and hemiagenesis of the thyroid gland, respectively. Dysgenesis was predominant on the left side in both sexes, without sex differences. At a young age, thyroid hemiagenesis did not alter body weight. In rats of both sexes with thyroid hemiagenesis, plasma total triiodothyronine and total triiodothyronine levels remained unchanged while plasma thyroid-stimulating hormone levels were significantly elevated in young rats. The remaining thyroid lobes increased in weight, but the follicular epithelial cells appeared normal in terms of their height and proliferating activities. On the side of thyroid dysgenesis, the parathyroid glands were normally localized and were situated at the same location as the contralateral glands. The ultimobranchial body remnants were localized at the level of the thyroid gland along with the cranial thyroid artery and vein, forming cell clusters or cystic structures and containing calcitonin-positive C-cells. In conclusion, Wistar/ST rats developed unilateral thyroid dysgenesis and may be novel and useful animal models for thyroid hemiagenesis in humans and for morphogenesis of pharyngeal pouch-derived organs.

Abdominal Ectopic Thyroid Tissue: The Man From Istanbul.

Thyroid ectopia is a rare finding below the diaphragm. It is characterized by normal thyroid parenchyma in unusual locations with preserved thyroid marker immunoreactivity. In this article, we present the first known case of thyroid tissue in the periappendiceal fat and discuss possible ethiopathogenic theories.

[A rare renal tumour : Ectopic thyroid tissue in the kidney]. / Der seltene Nierentumor : Renales ektopes Schilddrüsengewebe.

During a nephrectomy of a nonfunctioning, tumour-bearing kidney we found ectopic thyroid tissue in the kidney. This location of ectopic thyroid tissue has not been described before. In general, ectopic thyroid tissue is uncommon and rather found in the cervical region or upper mediastinum. A 131-iodine whole-body scan is the most precise method to detect the presence of ectopic thyroid tissue. It is often difficult to distinguish between benign and differentiated malignant thyroid tissue.

The value of scintigraphy, computed tomography, magnetic resonance imaging, and single-photon emission computed tomography/computed tomography for the diagnosis of ectopic thyroid in the head and neck: A STROBE-compliant retrospective study.

Because of its rarity, the exact imaging features of ectopic thyroid are poorly known.To analyze the value of scintigraphy, computed tomography (CT), magnetic resonance imaging (MRI), and single-photon emission computed tomography (SPECT)/CT in the diagnosis of ectopic thyroid in the head and neck.First, we retrospectively analyzed the scintigraphy, CT, MRI, and SPECT/CT images from 25 masses (22 patients) suspected of head and neck ectopic thyroid from 2006 to 2017 at the Shanghai Ninth People's Hospital. Each mass was imaged by nuclear imaging (scintigraphy with or without SPECT/CT) and radiological exam (CT and/or MRI). Pathological examination was considered as the gold standard. Secondly, thirteen malignant ectopic thyroids in the head and neck reported in the English literature from 2001 to 2017 were retrieved for comparison.The accuracy of scintigraphy was not significantly higher than that of CT (94.7%, vs 89.5%, P > .99) or MRI (92.3%, vs 84.6%, P > .99). Five masses which underwent scintigraphy with SPECT/CT were all true positive, while 1 was false negative on MRI, and 2 were false negative on CT. Compared to the benign ectopic thyroids in our study, the 13 malignant ectopic thyroids retrieved from the literature were grossly the same in shape, margins, and invasion on CT or MRI.The number of patients was limited, but scintigraphy combined with SPECT/CT could be a reliable method for the diagnosis of ectopic thyroid. Benign and malignant ectopic thyroids appear to be similar in shapes, margins, and invasion on CT or MRI.

Lymphnode metastasis of thyroid cancer misinterpreted as lateral aberrant thyroid 40 years before identification of primary tumor. Case report and review of the literature.

The differential diagnosis between lateral ectopic thyroid tissue with orthotopic normal gland and metastatic thyroid carcinoma is challenging. Lateral cervical site is a very rare location for ectopic tissue since only a few cases have been reported. The peculiarity of this clinical case is the finding of a thyroid carcinoma forty years after surgical resection of the ectopic thyroid lesion. This asynchronous association, never reported in literature, raises the question of the differential diagnosis between a true ectopic aberrant thyroid and an early lymph node metastasis from an occult thyroid carcinoma, evident in the primitive site many years later. Several elements, which will be matter of discussion, seem to favour the latter hypothesis.This case, although isolated, suggests that any lateral cervical mass, comprising thyroid tissue, should be regarded as a metastasis of thyroid carcinoma until proven otherwise. Carefull investigation of thyroid gland is mandatory.

Mediastinal ectopic thyroid diagnosed by endobronchial ultrasound-guided transbronchial needle aspiration: Report of three cases.

An ectopic thyroid gland results from the abnormal migration of the thyroid in the course of its development. Primary ectopic mediastinal thyroid is very rare and occurs in less than 1% of all goiters that can be surgically excised. Ectopic thyroid tissue has a characteristic sonographic appearance as smooth-bordered, homogeneous, hypoechoic tissue with fine specular echoes. We report 3 cases of mediastinal ectopic thyroid diagnosed by endobronchial ultrasound-guided transbrochial needle aspiration biopsy.

Thyroid hemiagenesis and Hashimoto's thyroditis-diagnostic and treatment pitfalls.

BACKGROUND: Thyroid hemiagenesis (TH) is a rare congenital disease with absence of a thyroid lobe; most patients have no clinical symptoms. The etiology of TH remains unclear. In this paper, we describe a rare case of TH and congenital absence of the ipsilateral parathyroid gland, found during the operation, combined with the autoimmune disease Hashimoto's thyroiditis, also known as chronic lymphocytic thyroiditis. CASE PRESENTATION: A 31-year-old woman was admitted to our hospital because of a mass in the right neck. Surgical exploration validated the absence of the left lobe of the thyroid and parathyroid glands, and pathological examination of the excised nodules confirmed Hashimoto's thyroiditis. Patients with TH might show accompanying absence of the ipsilateral parathyroid gland. The case described here, in which TH was combined with Hashimoto's thyroiditis, is rare in the medical literature. The operation should be ended at once if Hashimoto's thyroiditis is diagnosed during surgery. CONCLUSIONS: Absence of thyroid lobe may accompany with a congenital absence of the ipsilateral parathyroid gland and Hashimoto's thyroiditis. Fine needle aspiration is essential to diagnosis and decision-making of the treatment.

Ectopic thyroid tissue: unusual differential diagnosis of cervical paraganglioma.

Ectopic thyroid tissue (ETT) lateral to the midline is rare. Its occurrence in the carotid bifurcation is exceptional. We present a 45 years woman who consulted with a slow growing right cervical swelling. Clinical examination Ultrasonography, contrast enhanced CT and cervical MRI concluded to a paraganglioma. Intra-operatively, the tumor didn't have the characteristic aspect of a paraganglioma. Complete excision was performed. Histology concluded to an ectopic micro-vesicular thyroid adenoma.Previous literature was reviewed to summarize clinical and radiologic characteristics of such rare entity. Despite its rarity, ETT must be included in the differential diagnosis of cervical paraganglioma.

Thyroid Hemiagenesis: Incidence, Clinical Significance, and Genetic Background.

Context: Thyroid hemiagenesis (THA) constitutes a rare, congenital disorder that is characterized by an absence of one thyroid lobe. Because the pathogenesis and clinical significance of this malformation remain undefined, specific clinical recommendations are lacking, especially for asymptomatic cases. Evidence Acquisition: The PubMed database was searched (years 1970 to 2017), and the following terms were used to retrieve the results: "thyroid hemiagenesis," "thyroid hemiaplasia," "one thyroid lobe agenesis," and "one thyroid lobe aplasia." Subsequently, reference sections of the retrieved articles were searched. Evidence Synthesis: There is a noticeable susceptibility of subjects with THA to develop additional thyroid and nonthyroidal pathologies. In pathogenesis of concomitant thyroid pathologies, a chronic elevation in thyroid-stimulating hormone values may play an important role. Thus far, genetic studies failed to find a common genetic background of the anomaly, and the potential underlying cause was identified in a minority of the cases. Conclusions: Patients with THA are prone to develop additional thyroid pathologies and theoretically might benefit from l-thyroxine treatment to lower the thyrotropin levels to those observed in the normal population. However, further research should be done to ascertain whether such intervention early in life would prevent development of associated thyroid conditions. At least, increased vigilance should be maintained to reveal all of the concomitant disorders as soon as possible during follow-up examinations. Application of high-throughput technologies enabling a genome-wide search for novel factors involved in thyroid embryogenesis might be the next step to expand the knowledge on THA pathogenesis.

[Ectopic thyroid tissue with a primary carcinoma].

Ectopic thyroid tissue is a result of abnormal embryologic development and migration of the thyroid gland. It has a prevalence of one per 100,000-300,000, and the risk of malignant transformation in ectopic thyroid tissue is rare. We present a rare case of perivesical ectopic papillary thyroid carcinoma in a 76-year-old man with a normal orthotopic thyroid gland. A total thyroidectomy was performed, and the pathology report showed normal thyroid tissue with no neoplastic involvement. The patient was treated with radioactive iodine, and a control scintigraphy was without any signs of activity.