Approach to the diagnosis and treatment of neonatal hypothyroidism

Congenital hypothyroidism, occurring in 1:3000 newborns, is one of the most common preventable causes of mental retardation. Neurodevelopmental outcome is inversely related to the age of diagnosis and treatment. Infants detected through newborn screening programs and started on l-T(4) in the first few weeks of life have a normal or near-normal neurodevelopmental outcome. The recommended starting dose of l-T(4) (10-15 μg/kg · d) is higher on a weight basis than the dose for children and adults. Tailoring the starting l-T(4) dose to the severity of the hypothyroidism will normalize serum T(4) and TSH as rapidly as possible. It is important to obtain confirmatory serum thyroid function tests before treatment is started. Further diagnostic studies, such as radionuclide uptake and scan and ultrasonography, may be performed to determine the underlying cause of hypothyroidism. Because results from these tests generally do not alter the initial treatment decision, however, these diagnostic studies are rarely indicated. The developing brain has a critical dependence on thyroid hormone for the first 2-3 yr of life; thus, monitoring occurs at more frequent intervals than in older children and adults. Serum free T(4) and TSH should be checked at intervals frequent enough to ensure timely adjustment of l-T(4) dosing and to keep serum free T(4) and TSH levels in target ranges. Given the success of early detection and treatment of neonates with congenital hypothyroidism, a public health mandate should be to develop similar programs for the 75% of babies worldwide who are born in areas without newborn screening programs.

Early weaning PCB 95 exposure alters the neonatal endocrine system: thyroid adipokine dysfunction

Polychlorinated biphenyls (PCBs) are persistent environmental pollutants that can severely disrupt the endocrine system. In the present study, early-weaned male rats were administered a single dose of 2,3,6-2',5'-pentachlorinated biphenyl (PCB 95; 32 mg/kg per day, by i.p. injection) for two consecutive days (postnatal days (PNDs) 15 and 16) and killed 24 and 48 h after the administration of the last dose. Compared with the control group, administration of PCB 95 induced a reduction (P<0.01) in serum concentrations of thyroxine, triiodothyronine, and GH and an increase (P<0.01) in the serum concentration of TSH at PNDs 17 and 18. These conspicuous perturbations led to some histopathological deterioration in the thyroid gland characterized by follicular degeneration, edema, fibrosis, hemorrhage, luminal obliteration, and hypertrophy with reduced colloidal contents at PND 18. The dyshormonogenesis and thyroid dysgenesis may be attributed to the elevation of DNA fragmentation at PNDs 17 and 18. Furthermore, this hypothyroid state revealed higher (P<0.01) serum concentrations of leptin, adiponectin, and tumor necrosis factor and lower (P<0.01) serum concentrations of IGF1 and insulin at both PNDs compared with the control group. Interestingly, the body weight of the neonates in the PCB 95 group exhibited severe decreases throughout the experimental period in relation to that of the control group. These results imply that PCB 95 may act as a disruptor of the developmental hypothalamic-pituitary-thyroid axis. Hypothyroidism caused by PCB 95 may impair the adipokine axis, fat metabolism, and in general postnatal development. Thus, further studies need to be carried out to understand this concept.

Increased risk of thyroid pathology in patients with thyroid hemiagenesis: results of a large cohort case-control study

OBJECTIVE

Thyroid hemiagenesis (THA) is an anomaly resulting from the developmental failure of one thyroid lobe. Etiopathogenesis, clinical significance, and management of patients in whom THA is diagnosed are still a matter of debate. The aim of the study is to provide the first systematic analysis of a large cohort of subjects with THA.

DESIGN

Forty patients with THA are described in comparison to a control group of 80 subjects with fully developed thyroid gland.

METHODS

Serum concentrations of thyrotropin (TSH), free thyroxine (FT(4)), free triiodothyronine (FT(3)), and thyroid autoantibodies were measured. In 37 patients, thyroid ultrasonography and Tc-99m thyroid scintiscan were performed, followed by fine-needle aspiration biopsy if indicated. The remaining archival three cases were diagnosed with the use of I-131 scintiscan under basal conditions and after TSH stimulation.

RESULTS

Patients with THA, while usually clinically euthyroid, presented with significantly higher levels of TSH and FT(3) as well as with higher FT(3)/FT(4) concentration in comparison to the control group. Furthermore, a higher incidence of associated functional, morphological, and autoimmune thyroid disorders in patients with THA was observed when compared to subjects with bilobate thyroid (P<0.05).

CONCLUSIONS

Our results revealed that individuals with THA are more likely to develop thyroid pathology. The observed high incidence of associated pathologies is presumably due to long-lasting TSH overstimulation. Therefore, THA diagnosis should be followed by systematic observation and adequate levothyroxine treatment in patients with elevated TSH level.

A high prevalence of dual thyroid ectopy in congenital hypothyroidism: evidence for insufficient signaling gradients during embryonic thyroid migration or for the polyclonal nature of the thyroid gland?

BACKGROUND

Thyroid ectopy results from the failure of the thyroid precursor cells to migrate from the primordial pharynx to the anterior part of the neck. Most ectopic thyroids are revealed by congenital hypothyroidism and present as a single round mass at the base of the tongue, with no other thyroid tissue. However, some cases have dual ectopy, with part of the tissue having partially migrated. We hypothesized that this occurs more frequently than previously reported.

METHODS

To determine the prevalence of dual ectopy, we reviewed the pertechnetate scintigraphies of 81 patients with congenital hypothyroidism from thyroid ectopy diagnosed between 2002 and 2011 at our institution.

RESULTS

We report a series of seven cases (9%) of dual ectopy, representing an incidence ranging from 1:50,000 to 1:70,000.

CONCLUSIONS

Almost one in 10 cases with congenital hypothyroidism due to thyroid ectopy has dual ectopy. This suggests that two populations of cells diverged at an early stage of development, which may arise from insufficient signaling gradients in surrounding tissues during early organogenesis or may indirectly support the polyclonal nature of the thyroid.

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.

New insight into ectopic thyroid glands between the neck and maxillofacial region from a 42-case study

BACKGROUND

Ectopic thyroid is a rare disease. In the present study at the 9th People's Hospital in Shanghai, China, 42 patients' ectopic thyroid glands between the neck and maxillofacial region were subjected to a retrospective and transverse study based on data from 1978 to 2012 to explore the natural characteristics of ectopic thyroid.

METHODS

The patients' clinical data were collected. In addition, scintigraphy (Tc-99 m, Iodine-131), CT scan, histology and pathology were performed. The protein expression of thyroid transcription factor-1 (TTF-1), thyroglobulin (TG), calcitonin (CT), Ki-67 and parathyroid hormone (PTH) were analyzed from paraffin wax-stored specimens of ectopic thyroid tissue compared with those of orthotopic thyroid tissue.

RESULTS

There were 42 total ectopic thyroid patients, approximately 1.24 patients per year on average at our hospital. These patients were aged from 6 to 85 years old, and there were 35 females (83.3 %), seven males (16.7 %). In total, 27 of the patients had lingual thyroid (64 %); seven, sublingual thyroid (17 %); five, dual areas occupied by ectopic thyroid (12 %) and three, other types (7 %). The following conditions were also presented: nodular goiter (13 %), adenoma (8.7 %) and Hashimoto's thyroiditis (4.3 %), no malignancy and no accompanying ectopic parathyroid. TTF-1 expression was significantly higher in ectopic samples than that in orthotopic samples (P = 0.007), but CT and Ki-67 levels displayed no difference. PTH was negative in ectopic tissue.

CONCLUSION

Ectopic thyroid is a rare disease and females were more prone to the disease. The most frequent location was lingual thyroid. Nodular goiter, adenoma and Hashimoto's thyroiditis was observed as orthotopic thyroid without accompanying ectopic parathyroid. TTF-1 was highly expressed in ectopic tissue, which may be related to abnormal embryogenesis leading to the thyroid gland being in an abnormal position. The expression of calcitonin (CT) and Ki-67 was not increased, and there were no malignant cells in any sample, which could indicate that it is not easy for ectopic thyroids to become malignant between the neck and maxillofacial region.

Ectopic thyroid of the pancreas: A case report and literature review

RATIONALE

Ectopic thyroid is commonly found in the neck region. Intra-abdominal ectopic thyroid is extremely rare, with only 2 cases reported in the pancreatic region. Very few reports have described detailed imaging findings of intra-abdominal ectopic thyroid.

PATIENT CONCERNS

A 73-year-old woman with aggravated recurrent right upper quadrant pain was found to have a retroperitoneal mass at the head of pancreas. Abdominal computed tomography (CT) showed a well-defined, high attenuated (56HU) mass measured of 60 × 50 mm in diameter, that exhibited heterogeneous contrast enhancement throughout the 3 phases.

DIAGNOSIS

Neuroendocrine neoplasm was suspected.

INTERVENTIONS

Following discussions with the patient, she refused fine needle aspiration cytology; however, she underwent total resection of the mass and had an uneventful clinical course. Histopathological examination showed thyroid tissue with TTF-1 and TGB positivity, and BRAF negativity, indicating a benign variant.

OUTCOMES

The patient had no signs of relapse with normal thyroid hormone levels after 2 years of follow up.

LESSONS

Ectopic thyroid tissue should be considered when patients present with similar imaging findings in abdomen. We review all reported cases of abdominal ectopic thyroid tissue to provide specific evidence for the diagnosis and treatment of this rare entity.

Enhanced Canonical Wnt Signaling During Early Zebrafish Development Perturbs the Interaction of Cardiac Mesoderm and Pharyngeal Endoderm and Causes Thyroid Specification Defects

Background: Congenital hypothyroidism due to thyroid dysgenesis is a frequent congenital endocrine disorder for which the molecular mechanisms remain unresolved in the majority of cases. This situation reflects, in part, our still limited knowledge about the mechanisms involved in the early steps of thyroid specification from the endoderm, in particular the extrinsic signaling cues that regulate foregut endoderm patterning. In this study, we used small molecules and genetic zebrafish models to characterize the role of various signaling pathways in thyroid specification. Methods: We treated zebrafish embryos during different developmental periods with small-molecule compounds known to manipulate the activity of Wnt signaling pathway and observed effects in thyroid, endoderm, and cardiovascular development using whole-mount in situ hybridization and transgenic fluorescent reporter models. We used the antisense morpholino (MO) technique to create a zebrafish acardiac model. For thyroid rescue experiments, bone morphogenetic protein (BMP) pathway induction in zebrafish embryos was obtained by manipulation of heat-shock inducible transgenic lines. Results: Combined analyses of thyroid and cardiovascular development revealed that overactivation of Wnt signaling during early development leads to impaired thyroid specification concurrent with severe defects in the cardiac specification. When using a model of MO-induced blockage of cardiomyocyte differentiation, a similar correlation was observed, suggesting that defective signaling between cardiac mesoderm and endodermal thyroid precursors contributes to thyroid specification impairment. Rescue experiments through transient overactivation of BMP signaling could partially restore thyroid specification in models with defective cardiac development. Conclusion: Collectively, our results indicate that BMP signaling is critically required for thyroid cell specification and identify cardiac mesoderm as a likely source of BMP signals.

DUOX2 and DUOXA2 Variants Confer Susceptibility to Thyroid Dysgenesis and Gland-in-situ With Congenital Hypothyroidism

Background: Thyroid dysgenesis (TD), which is caused by gland developmental abnormalities, is the most common cause of congenital hypothyroidism (CH). In addition, advances in diagnostic techniques have facilitated the identification of mild CH patients with a gland-in-situ (GIS) with normal thyroid morphology. Therefore, TD and GIS account for the vast majority of CH cases. Methods: Sixteen known genes to be related to CH were sequenced and screened for variations by next-generation sequencing (NGS) in a cohort of 377 CH cases, including 288 TD cases and 89 GIS cases. Results: In our CH cohort, we found that DUOX2 (21.22%) was the most commonly variant pathogenic gene, while DUOXA2 was prominent in TD (18.75%) and DUOX2 was prominent in GIS (34.83%). Both biallelic and triple variants of DUOX2 were found to be most common in children with TD and children with GIS. The most frequent combination was DUOX2 with DUOXA1 among the 61 patients who carried digenic variants. We also found for the first time that biallelic TG, DUOXA2, and DUOXA1 variants participate in the pathogenesis of TD. In addition, the variant p.Y246X in DUOXA2 was the most common variant hotspot, with 58 novel variants identified in our study. Conclusion: We meticulously described the types and characteristics of variants from sixteen known gene in children with TD and GIS in the Chinese population, suggesting that DUOXA2 and DUOX2 variants may confer susceptibility to TD and GIS via polygenic inheritance and multiple factors, which further expands the genotype-phenotype spectrum of CH in China.

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.

Identification of a novel pax8 gene sequence variant in four members of the same family: from congenital hypothyroidism with thyroid hypoplasia to mild subclinical hypothyroidism

BACKGROUND

Congenital hypothyroidism is often secondary to thyroid dysgenesis, including thyroid agenesis, hypoplasia, ectopic thyroid tissue or cysts. Loss of function mutations in TSHR, PAX8, NKX2.1, NKX2.5 and FOXE1 genes are responsible for some forms of inherited congenital hypothyroidism, with or without hypoplastic thyroid. The aim of this study was to analyse the PAX8 gene sequence in several members of the same family in order to understand whether the variable phenotypic expression, ranging from congenital hypothyroidism with thyroid hypoplasia to mild subclinical hypothyroidism, could be associated to the genetic variant in the PAX8 gene, detected in the proband.

METHODS

We screened a hypothyroid child with thyroid hypoplasia for mutations in PAX8, TSHR, NKX2.1, NKX2.5 and FOXE1 genes. We studied the inheritance of the new variant R133W detected in the PAX8 gene in the proband's family, and we looked for the same substitution in 115 Caucasian European subjects and in 26 hypothyroid children. Functional studies were performed to assess the in vitro effect of the newly identified PAX8 gene variant.

RESULTS

A new heterozygous nucleotide substitution was detected in the PAX8 DNA-binding motif (c.397C/T, R133W) in the proband, affected by congenital hypothyroidism with thyroid hypoplasia, in his older sister, displaying a subclinical hypothyroidism associated with thyroid hypoplasia and thyroid nodules, in his father, affected by hypothyroidism with thyroid hypoplasia and thyroid nodules, and his first cousin as well, who revealed only a subclinical hypothyroidism. Functional studies of R133W-PAX8 in the HEK293 cells showed activation of the TG promoter comparable to the wild-type PAX8.

CONCLUSIONS

In vitro data do not prove that R133W-PAX8 is directly involved in the development of the thyroid phenotypes reported for family members carrying the substitution. However, it is reasonable to conceive that, in the cases of transcriptions factors, such as Pax8, which establish several interactions in different protein complexes, genetic variants could have an impact in vivo.

Thyroid hemiagenesis, Graves' disease and differentiated thyroid cancer: a very rare association: case report and review of literature

OBJECTIVE

Thyroid hemiagenesis is a rare congenital disorder characterized by the absence of a lobe and/or of isthmus. Studies on the association between thyroid hemiagenesis, Graves' disease and differentiated thyroid cancer are rare.

CASE PRESENTATION

We describe the medical and surgical history of a patient in whom a molecular evaluation was performed. A 36-year-old man presented with symptoms and signs of hyperthyroidism of a few months' duration. Hyperthyroidism was confirmed biochemically and anti-TSH-receptor antibodies were positive. Thyroid ultrasonography showed no left lobe and demonstrated a diffused enlargement of the right lobe; an ipoechoic, non-homogenous nodule 15 millimeters in size was identified in the middle part of the lobe. A 99mTc-pertechnetate thyroid scintigraphy (111 MBq) confirmed thyroid hemiagenesis due to the absence of the left lobe. Treatment with methimazole (30 mg/day) was started. As the patient's hyperthyroidism improved, he underwent fine-needle needle aspiration cytology (FNAC) of the right nodule. Cytology was suspicious for malignancy (THY4) and the patient was referred for surgery. Histopathological findings revealed a papillary thyroid carcinoma. The molecular analysis did not show PAX8 or TSHR mutations in the thyroid tissue nor mutations of BRAF, H-RAS, N-RAS or K-RAS genes in the tumor.

CONCLUSION

Though thus far studies on the association of thyroid hemiagenesis, Graves' disease and differentiated thyroid cancer are extremely rare, the possibility of the development of thyroid cancer must be taken into account in patients affected by thyroid hemiagenesis and the nodular variant of Graves' disease.

Importance of ectopic thyroid tissue detected in the midline of the neck: single center experience

OBJECTIVE

Ectopic thyroid tissue (ETT) is a rare abnormality of the thyroid gland and the true prevalence and importance is not known. The aim of this study was to evaluate ultrasonography (US) guided fine needle aspiration biposy (FNAB) results, sonographic features, and frequency of ETT detected in the midline of the neck.

SUBJECTS AND METHODS

Five thousand five hundred and twenty outpatients who were referred to our thyroid clinic between September 2010 and April 2012 and underwent thyroid US, were retrospectively analyzed. Patients with ETT, detected in the midline of the neck in US were included in the study. Thyroid functions, sonographic features, and US guided FNAB results were evaluated.

RESULTS

There were 81 (81.8%) female and 18 (18.2%) male patients with a mean age of 50.9 ± 11.7. The ETT in the midline was present in 1.79% (99/5,520) of the patients. In the majority of the patients, benign sonographic features (isoechoic, regular margin, type 1 vascularization) were detected. There were 92 (92.9%) patients with a previous history of thyroidectomy and all were histopathologically benign. In 7 (7.1%) patients, there was no history of thyroid operation. FNAB results of ETT were benign.

CONCLUSION

This study evaluated the importance of ETT detected incidentally in the midline of the neck. Especially in patients with a history of thyroidectomy, the thyroid masses in the midline of the neck can be found as incidental with imaging methods. Our results suggests that the incidence of malignancy in this group is much lower than orthotopic thyroid nodules and they are often benign.

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.

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.

Functional characterization of the novel sequence variant p.S304R in the hinge region of TSHR in a congenital hypothyroidism patients and analogy with other formerly known mutations of this gene portion

CONTEXT

Thyroid dysgenesis may be associated with loss-of-function mutations in the thyrotropin receptor (TSHR) gene.

OBJECTIVES

The aim of this study was to characterize a novel TSHR gene variant found in one patient harboring congenital hypothyroidism (CH) from a cohort of patients with various types of thyroid defects.

MATERIALS AND METHODS

This cross-sectional cohort study involved 118 patients with CH and their family members, including 45 with familial and 73 with sporadic diseases. The thyroid gland was normal in 23 patients, 25 patients had hypoplasia, 25 hemithyroid agenesis, 21 had athyreosis, and 21 had ectopy. Genomic DNA was extracted, and 10 exons of the TSHR gene were amplified and sequenced. Mutations in other candidate genes were investigated. Ortholog alignment was performed, and TSHR functional assays were evaluated.

RESULTS

We identified one previously unknown missense variation in the hinge region (HinR) of the TSHR gene (p.S304R) in one patient with thyroid hypoplasia. This variant is conserved in our ortholog alignment. However, the p.S304R TSHR variant presented a normal glycosylation pattern and signal transduction activity in functional analysis.

CONCLUSION

We report the ocurrence of a novel nonsynonymous substitution in the HinR of the large N-terminal extracellular domain of the TSHR gene in a patient with thyroid hypoplasia. In contrast with four others in whom TSHR mutations of the hinge portion were previously identified, the p.S304R TSHR variation neither affected TSH binding nor cAMP pathway activation. This TSHR gene variant was documented in a CH patient, but the current data do not support its role in the clinical phenotype.

A case of pediatric ectopic thyroid in lateral lymph nodes

On average, ectopic thyroids are positioned in the embryotic decent path that emerges as a lingual thyroid or a thyroglossal duct cyst. It is uncommon for ectopic thyroids to be located in the lateral neck, which only represents 1%-3% of all cases. Any ectopic thyroids that emerge in the posterior lateral neck in pediatric patients should be regarded as an extremely unique case. We report a 13-year-old boy with ectopic thyroid tissue in the cervical lymph nodes with orthotopic euthyroid thyroid. The masses were located on the left posterior triangle area, which were confirmed as histologic benign thyroid tissue without any malignancy in the head and neck. Authors suggest that this case supports the benign lymphatic transport theory of lateral ectopic thyroid.

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.

[Goiter on pre-sternal thyroid dysgenesis]

L'hétérotopie thyroïdienne est une localisation anormale de tissus thyroïdiens normaux coexistant avec un organe normal et de localisation normale. Elle se distingue de l'ectopie thyroïdienne et d'une métastase du cancer de la thyroïde. Nous rapportons un cas d'hétérotopie thyroïdienne pré-sternale chez une femme de 65 ans afin de discuter le mécanisme de la migration de la thyroïde, le problème diagnostique et thérapeutique posé par cette topographie exceptionnelle. L'origine thyroïdienne de la masse est confirmée par l'histologie. Dans les lieux isolés, la chirurgie d'exérèse reste le seul moyen pour avoir le diagnostic et pour traiter les patients.

[Ectopic thyroid: the role of thyroid scan]

Ectopic thyroid is a rare malformative disease. We report an additional case of ectopic right thyroid lobe, detected during CT scan evaluation of a left lateral cervical mass.

[Congenital hypothyroidism secondary to thyroid hypoplasia detected in adulthood]

The anatomical location of the thyroid gland and its hormone byosinthesis are regulated by the expression of certain genes, whose disruption leads to the so-called thyroid dysgenesis: agenesis, ectopia and hypoplasia, and to dyshormonogenesis. We present the case of a patient with mental retardation and hypothyroidism whose diagnosis was made in adulthood. Biochemical determinations confirmed the diagnosis without evidence of thyroid autoimmunity. This patient represents the extended evolution of a thyroid hypofunction, which lasted in an unsuspected way for 53 years, with important consequences of this deficiency at diagnosis. Exogenous therapy achieved great improvement in clinical symptoms, but did not reverse the neurological damage attributable to the lack of thyroid hormone necessary for fetal development. The necropsy revealed little thyroid tissue in the neck corresponding to eutopic thyroid hypoplasia. The discovery of a remaining thyroid of less than 1 cm justified the patient survival up to old age.