Thyroid hemiagenesis in an endemic goiter area diagnosed by ultrasonography: report of sixteen patients

Parathyroid Carcinoma in a Patient With Secondary Hyperparathyroidism and Thyroid Hemiagenesis: A Case Report and Review of the Literature

Parathyroid carcinoma is a rare endocrine tumor. Parathyroid carcinoma in patients with secondary hyperparathyroidism due to chronic kidney disease is also rare. In addition, thyroid hemiagenesis is a rare congenital anomaly. We report an extremely rare case of parathyroid carcinoma in a patient with secondary hyperparathyroidism and thyroid hemiagenesis. We also present a review of the literature of this rare entity. We also discuss the surgical procedure performed for this patient. Our review of the literature found 34 case reports of parathyroid carcinoma in patients undergoing dialysis due to chronic renal failure; 14 reports of thyroid hemiagenesis with parathyroid disease; and no previous reports of thyroid hemiagenesis with secondary hyperparathyroidism and parathyroid carcinoma. Although surgical treatment of parathyroid carcinoma requires combined resection with the thyroid, peritracheal dissection with total parathyroidectomy, and monitoring intact parathyroid hormone as a tumor marker, our procedure preserved the patient's thyroid function. There has been no evidence of recurrence for over 8 years.

Computed tomography findings of thyroid hemiagenesis: differentiation from hemithyroidectomy

OBJECTIVES

Thyroid hemiagenesis is a rare congenital anomaly characterized by the lack of development of one thyroid lobe. The purpose of this study was to evaluate computed tomography (CT) findings of thyroid hemiagenesis and to establish useful CT criteria for differentiating thyroid hemiagenesis from the hemithyroidectomy state.

METHODS

The CT images of 11 patients with thyroid hemiagenesis were retrospectively reviewed and compared with those of 100 (49 left and 51 right) patients in a hemithyroidectomy state. Image analysis was performed according to the following CT parameters: (a) side of thyroid hemiagenesis, (b) edge of the medial end of the remnant thyroid gland, (c) location of the medial end of the remnant thyroid gland, expressed as the angle of the medial end and (d) any other thyroid abnormality observed during the initial examination.

RESULTS

The missing lobe occurred more often in the left than in the right lobe (72.7% vs. 27.3%) as well as concomitant isthmus agenesis (100% vs. 37.5%). The sharp edge of the medial end of the remnant thyroid gland was more common in thyroid hemiagenesis (64%) than in hemithyroidectomy (26%) (P = 0.0153). In left thyroid hemiagenesis, the angle of the medial end (63%) was more frequently >  + 30° than in hemithyroidectomy (0%) (P < 0.0001). Two patients presented with hypothyroidism; the remaining nine showed a normal thyroid function. The associated thyroid diseases were autoimmune thyroiditis (n = 1) and papillary thyroid carcinoma (n = 1).

CONCLUSIONS

The sharp edge of the medial end of the remnant thyroid gland and an angle of >  + 30° for the medial end in cases wherein the left lobe is absent are useful CT features for distinguishing thyroid hemiagenesis from hemithyroidectomy.

Thyroid Hemiagenesis: Narrative Review and Clinical Implications

Thyroid Hemiagenesis (THA) is an uncommon, congenital anomaly defined by the absence of one thyroid lobe with or without the isthmus. Reports suggest it may be found more often in regions endemic for hypothyroidism. Genetic abnormalities are thought to have a role based on findings in monozygotic twins. Most cases are sporadic, however familiar clusters have also been documented. It is found more frequently in females. A majority of patients report no symptoms and THA is found incidentally during investigations or intraoperatively. THA is usually associated with normal thyroid function, but it can present with thyroid hypofunction.

Since a majority of patients are asymptomatic, there are no specific recommendations for management. Ultrasound imaging and thyroid scintigraphy using technetium or iodine are useful in diagnosis. Its clinical importance occurs when the remnant thyroid lobe requires excision leading to the lifelong requirement for thyroxine supplementation.

Published English literature (Medline, PubMed, and Embase databases) was searched. Medical subject headings (MeSH) terms used were “thyroid hemiagenesis,” “one thyroid lobe,” and “thyroid aplasia”. Case reports, case series, and original articles were selected to provide a framework for this review.

Articles reviewed were published in the past 20 years. The association of THA with thyroid cancer was explored. In this group, the F:M ratio was 3.25:1. Left THA constituted 53% of cases, right THA in 29.4%, and isthmus absence in 17.6% of cases. Also, the authors investigated the link between THA and hyperparathyroidism, both left and right THA are seen in an equal number of cases in the hyperparathyroidism subgroup. In patients with THA and Grave’s disease, left THA was seen in a majority of cases (86.7%), while an equal number of left and right THA was observed in patients with Hashimoto’s thyroiditis. In addition, congenital abnormalities associated with THA were observed, the left THA was seen in 60% and right THA in 40% of cases of this subgroup.

The summative review provided a detailed insight into the epidemiology, aetiopathogenesis, genetics, symptomatology, diagnosis, and treatment for THA by combining findings and results from almost a hundred research papers from around the world. THA remains a poorly understood, often incidentally detected, abnormality in euthyroid patients undergoing investigations and treatment for other thyroid disorders.

Hemiagenesis of the thyroid gland detected by coincidence-what is the clinical relevance? : Case report and review of the literature

Hemiagenesis of the thyroid gland (THA) represents a rare congenital anomaly. It is characterized by the absence of one thyroid lobe, and sometimes the isthmus as well. It can occur with all kinds of other thyroid pathologies that may be present in the remaining thyroid lobe. A case of a 21-year-old male patient is presented; he sought a thyroid consultation because of hair loss, fatigue, and problems concentrating, thus raising the suspicion of hypothyroidism. Thyroid function was normal, but sonography of the thyroid gland revealed THA of the left lobe and the isthmus. The current knowledge concerning the genesis and the clinical consequences of THA are discussed based on the current literature.

Thyroid hemiagenesis: a case report

Thyroid hemiagenesis is a rare entity in the literature. Developmental hemi-thyroid anomalies can result from either an abnormal descent or an agenesis of one lobe of the thyroid gland. This study aimed at presenting a thyroid hemiagenesis case incidentally diagnosed by neck ultrasonography (USG), who had complaints of pain and swelling in the neck. USG examination revealed lack of left thyroid lobe and multiple nodules in the right lobe. Fine Needle Aspiration Biopsy (FNAB) showed follicular neoplasia, and right subtotal thyroidectomy was performed. We report the rarity of the condition and emphasize the role of imaging techniques in preoperative diagnosis and subsequent management.

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.

A case report of 131I therapy for Graves' disease patient with hemiagenesis

RATIONALE

Thyroid hemiagenesis is a rare congenital dysplasia, whereas a variety of pathological changes may occur in residual thyroid lobe. The most frequently described pathology in residual thyroid lobe is Graves' hyperthyroidism. Although I therapy has been generally recommended as the preferred treatment for Graves' disease (GD), subjects relating to hemiagenesis are very limited, especially in China.

PATIENT CONCERNS

A 43-year-old female patient presented to our hospital on November 2014, with a 1-year history of palpitation, fatigue, and hand tremor. Her situation was getting worse within 2 months.

DIAGNOSIS

The thyroid function tests were suggestive of thyrotoxicosis. The technetium thyroid scintigraphy only showed an enlarged right lobe with increased tracer uptake. Then, the agenesis of left lobe and isthmus was confirmed by ultrasound and magnetic resonance imaging (MRI). Thus, a diagnosis of GD with hemiageneis of the left lobe and isthmus of thyroid was made.

INTERVENTIONS

Thiamazole was discontinued because of drug-induced hepatic injury. According to our procedures, the patient was treated by I.

OUTCOMES

Hypothyroidism was observed 3 months after I therapy. After replacement therapy with L-thyroxine (LT4), the state of euthyroid maintained.

LESSONS

Once hypothyroidism occurs, regular application of LT4 and review of thyroid function is very important. Thus, patients' compliance needs to be strengthened. Besides, we could not convince the family members of our patient to undergo ultrasonographic examination. The genetic factor of the agenesis could not be proved in this case.

Thyroid Carcinoma on the Side of the Absent Lobe in a Patient with Thyroid Hemiagenesis

Background

Thyroid carcinoma complicated by hemiagenesis is very rare, and previous reports have not described this cancer on the side of the absent lobe.

Methods and Results

We report the case of a 64-year-old woman in whom left thyroid hemiagenesis was discovered incidentally during investigations of abnormal sensation during swallowing. A tumorous 1.4 cm lesion was also found on the side of the absent lobe, left of the isthmus. Fine-needle aspiration biopsy revealed class V papillary carcinoma, but no lymph node metastases. Total thyroidectomy was performed for stage cT1bN0M0 carcinoma. Histopathology revealed normal thyroid tissues in the right lobe and isthmus, while the left lobe was absent. The mostly papillary carcinoma was adjacent to the truncated thyroid tissue, with a portion histologically consistent with poorly differentiated carcinoma.

Conclusions

All previously reported cases of thyroid cancer complicated by hemiagenesis have represented carcinoma occurring within the present lobe. This case is extremely rare.

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.

Prevalence and Characterization of Thyroid Hemiagenesis in Japan: The Fukushima Health Management Survey

BACKGROUND

Thyroid hemiagenesis is a rare congenital variant characterized by the lack of development of one thyroid lobe with no clinical manifestations.

METHODS

This study was performed to determine the prevalence and characteristics of thyroid hemiagenesis in a normal Japanese population. This cross-sectional study was performed from October 9, 2011, to April 30, 2015. In total, 299,908 children and young adults in the Fukushima Health Management Survey were examined to determine the presence of thyroid agenesis or hemiagenesis. Thyroid width, thickness, and length were measured in 292,452 of these subjects.

RESULTS

Thyroid agenesis was diagnosed in 13 subjects, and hemiagenesis was detected in 67 subjects (0.02%; 22.3/100,000 individuals). Although there was no significant sex-related difference (p = 0.067), the female:male ratio was 1.67:1.00. Females were significantly dominant in right hemiagenesis, while there was no difference in left hemiagenesis between males and females. The thyroid volumes at the 2.5th and 97.5th percentiles for age and body surface area were determined for each sex. Multivariate regression analysis showed that a large hemithyroid volume was independently associated with the presence of contralateral hemiagenesis (p < 0.001).

CONCLUSION

The prevalence of thyroid hemiagenesis in the present study is in agreement with that reported in other countries. The prevalence of right hemiagenesis was higher in females, and the larger contralateral lobe in patients with rather than without hemiagenesis may have been caused by a compensatory feedback mechanism to prevent hypothyroidism. In addition, the prevalence of hemiagenesis, especially right hemiagenesis, may be affected by sex-related factors similar to those in patients with an ectopic thyroid gland.

THYROID HEMIAGENESIS ASSOCIATED WITH GRAVES' DISEASE: A CASE REPORT AND REVIEW OF THE LITERATURE

Introduction

Thyroid hemiagenesis (TH) is a congenital developmental disorder. Most cases are euthyroid although hyperthyroidism, hypothyroidism, and malignancy may develop. We present a case of hemiagenesis with Graves' disease (GD) and review the literature about the association.

Case report

A 45-year-old female patient was admitted to the endocrinology department due to nausea and diarrhea. Her past medical history revealed hyperthyroidism diagnosed a year ago. On thyroid examination, right thyroid lobe was palpable, but left lobe and isthmus were not. Physical examination involving other organ systems was unremarkable except for fine tremor of the hands. Thyroid function tests revealed a high level of free T4 and T3 with a low serum TSH. Thyroid antibodies were all positive. Left lobe and isthmus were invisible on thyroid ultrasonography (US) and the right thyroid lobe measuring 44x18x12 mm was diffusely heterogeneous in echo texture. Thyroid scan using Technetium-99m showed increased homogeneous tracer uptake in the right lobe. The patient was diagnosed with TH and GD.

Discussion

In case of unilateral increased uptake on scintiscan, GD with hemiagenesis must be kept in mind in the differential diagnosis of autonomous solitary adenoma, postinflammatory atrophy of thyroid in Hashimoto's disease, focal or unilateral subacute thyroiditis, and primary or metastatic carcinoma. It is prudent to do thyroid ultrasound along with scintigram. US is a valuable tool for the quick diagnosis of TH and differential diagnosis from other causes.

Thyroid cancer in a patient with congenital thyroid hemiagenesis

We present a case with thyroid cancer in a patient with congenital thyroid hemiagenesis (absence of left lobe). This anatomic variation was diagnosed preoperatively by ultrasonography in a patient with nodular thyroidopathy in the right lobe; ultrasound-guided fine-needle aspiration (FNA_ confirmed the diagnosis of cancer. Recognition of this rare anatomical variant is important for the surgeon to avoid aggressive and potentially hazardous surgical manipulations during surgery to find the missing thyroid lobe.

Ultrasonographic and scintigraphic findings of thyroid hemiagenesis in a child: report of a rare male case

Thyroid hemiagenesis is a rare congenital anomaly in which one lobe of thyroid gland fails to develop. It is much rarer in males. There is a higher incidence of associated thyroid disorders in patients with thyroid hemiagenesis; therefore early and prompt diagnosis is important for children. We present the ultrasonographic and scintigraphic findings of thyroid hemiagenesis in an eight-year-old-boy. On ultrasonography (US), left lobe of the thyroid gland could not be demonstrated and the right lobe showed minimal hyperplasia. Its echogenicity was normal and no nodule was seen. On thyroid scintigraphy, left lobe of thyroid gland or any ectopic thyroid tissue could not be demonstrated, while the right lobe showed minimal hyperplasia. Without performing any invasive procedure, we enrolled the child in a follow-up program with the guidance of US and scintigraphy, which were effective both in making the final diagnosis of thyroid hemiagenesis and in evaluating the current status of the present thyroid tissue. In conclusion, if only one thyroid lobe is detected in a pediatric case initially with US or scintigraphy, the diagnosis of thyroid hemiagenesis should be suggested and, before any unnecessary or invasive attempt, the other complementary method (scintigraphy/US) should be performed.

Congenital thyroid hemiagenesis with multinodular goiter

Thyroid hemiagenesis is a rare form of thyroid dysgenesis characterized by an absence of half of the thyroid gland. Developmental hemi-thyroid anomalies can result from either an abnormal descent or an agenesis of one lobe of the thyroid gland. We report a case of a 40-year-old woman with history of a longstanding gradually progressive thyroid swelling without any complication. An ultrasonographic examination diagnosed the absence of the left thyroid lobe and enlargement of the right lobe, which was confirmed on a computed tomography (CT) angiogram and a radionuclide scan of the neck. A cytological examination showed nodular goiter with cystic degeneration. Right subtotal thyroidectomy was performed and histopathological examination confirmed adenomatous goiter with degenerative changes. We report the rarity of the condition and emphasize the role of a comprehensive radiological, cytological, and radionuclide algorithm for an accurate preoperative diagnosis and subsequent management.

Surgical strategy for primary hyperparathyreoidism with thyroid hemiagenesis

BACKGROUND

Thyroid hemiagenesis is a rare congenital anomaly, and still more rarely associated with primary hyperparathyroidism (pHPT). Due to the embryologic pathways of the thyroid and parathyroid glands, it remains unclear whether or not thyroid hemiagenesis may be linked to ipsilateral parathyroid agenesis, and consequently, surgical strategy for thyroid hemiagenesis associated pHPT (THAP) does not only depend on preoperative localization but also on the thyroid anomaly.

METHODS

Including the present case report, a total of nine cases with THAP retrieved from the literature were reviewed. Seven of nine cases had thyroid hemiagenesis on the left side, three out of nine showed a parathyroid adenoma on the contralateral side to the thyroid hemiagenesis.

CONCLUSIONS

Based on these cases, it can be concluded that the embryologic pathways of the thyroid and parathyroid glands are different, and in cases of THAP, parathyroid exploration should follow standard recommendations for pHPT surgery.

Thyroid isthmus agenesis associated with thyroid papillary carcinoma. [corrected]

A wide range of morphological varieties and developmental anomalies of the thyroid gland have been reported in literature such as hypoplasia, ectopy, hemiagenesis, and agenesis. Out of these, the incidence of agenesis of the thyroid isthmus is rare, and very few cases have been reported. In the present case report, a female patient was found with agenesis of thyroid isthmus with thyroid papillary carcinoma in the right lobe. In this article, we report a case of thyroid isthmus agenesis and reviewed the associated literature.

Thyroid Hemiagenesis Associated with Hashimoto's Thyroiditis

Thyroid hemiagenesis is a rare congenital anomaly resulting from failure of one thyroid lobe development. We report a 23-year-old female presented with Hashimoto's thyroiditis in left lobe, associated with hemiagenesis of right lobe and isthmus which was previously diagnosed as Graves' hyperthyroidism, but developed further into Hashimoto's thyroiditis after being treated with antithyroid drugs. The symptoms of hyperthyroidism in the current case led to the diagnostic confirmation by scintiscanning of an absent lobe. The antithyroid pharmacotherapy by thiamazole was used. However, due to symptoms of hypothyroidism, it was discontinued two months later, so thyroid hormone substitution was reintroduced. Antithyroid antibody studies and ultrasonography documented the presence of Hashimoto's thyroiditis.

A case of hemiagenesis of thyroid with double ectopic thyroid tissue

Developmental abnormalities of the thyroid gland are very rare. The most common abnormalities include ectopic thyroid tissues that are commonly seen in lingual or sublingual location, agenesis, and hemiagenesis of the thyroid gland. These developmental defects may or may not be associated with thyroid dysfunction. Our case is an 18-year-old male who presented with swelling in the neck of 4-year duration. Clinical examination revealed an oval-shape swelling in the left side of the thyroid gland. The ultrasound and the nuclear scan report revealed the presence of thyroid hemiagenesis of the right lobe with isthmus along with double ectopic thyroid tissue at suprahyoid and infrahyoid region. His thyroid function test showed elevated thyroid-stimulating hormone (TSH) and normal free T4. We report a very rare case of thyroid hemiagenesis with double ectopic thyroid tissue; and to the best of our knowledge, this is the first report in the world literature.

Thyroid hemiagenesis: a case series and review of the literature

PURPOSE

The purpose of this study is to present a case series and review recommendations within the literature concerning thyroid hemiagenesis.

MATERIALS AND METHODS

This is a (1) retrospective case series review of 5 patients and (2) literature review (using Medline) on thyroid hemiagenesis.

RESULTS

Most reported cases are female with the left thyroid lobe absent. Compensatory hypertrophy occurs in most thyroid remnants. Associated diagnoses in the remaining lobe include hyperthyroidism, hypothyroidism, simple and multinodular goiter, and carcinoma. There is no increased risk for the subsequent development of cancer in the remaining lobe, and empiric thyroidectomy is not justified.

CONCLUSIONS

Thyroid hemiagenesis is an uncommon presentation that is frequently asymptomatic and detected incidentally when imaging for another condition. Awareness of its existence can help prevent unnecessary interventions associated with incorrect assumptions in patient care.

Thyroid hemiagenesis: report of a case and review of literature

Our objective was to report an incidental finding of thyroid hemiagenesis in a patient who presented with a left neck mass, present a review of literature, and to discuss management of this diagnosis. Case report and review of literature. An internet-based literature search was performed via Pubmed with key words, "hemithyroid agenesis, thyroid hemiagenesis, absent thyroid gland". Clinical, pathological, radiologic data and follow up information is reported. A 55 year old woman with a left neck mass presented to our service. A diagnostic CT scan of the head and neck revealed an unrelated finding of an absent left thyroid lobe. A review of the CT imaging did not reveal ectopic thyroid tissue. A complete physical examination including a flexible laryngoscopy was unremarkable. The neck mass was pathologically a granulomatous lesion on surgical pathology. Thyroid function tests were within normal limits. In follow-up, patient remains asymptomatic. Hemithyroid agenesis is most commonly associated with hyperthyroidism, although, hypothyroidism has been reported. Pathology that can be associated in the remnant thyroid lobe includes adenocarcinoma, adenoma, multinodular goiter, and chronic thyroiditis. In counseling patients, it is important to educate them regarding these associated conditions and offer appropriate work up if indicated. Incidental thyroid agenesis with a negative work up can then be observed.

Right-sided hemiagenesis of the thyroid lobe and isthmus: A case report

Unilateral or bilateral hypoplasia or agenesis of one or both thyroid lobes, with or without isthmic agenesis, is a rare developmental anomaly. Hemiagenesis of the left lobe is far commoner than of the right. Clinically, these patients may be euthyroid, hyperthyroid, or hypothyroid. Ultrasonography is usually able to diagnose this condition easily, as we demonstrate in this case report of a 37-year-old lady with an incidentally detected thyroid nodule who was found to have hemiagenesis of the right lobe and isthmus.

Parathyroid adenoma on the ipsilateral side of thyroid hemiagenesis

We present a case of a parathyroid adenoma on the ipsilateral side of thyroid hemiagenesis-which, to our knowledge, is the third reported case of this entity. A 41-year-old man with nephrolithiasis was found to have elevated calcium and intact parathyroid hormone levels. Both ultrasound and technetium sestamibi scintigraphy with single photon emission computed tomography confirmed left thyroid hemiagenesis and an adenoma in the left inferior thyroid bed. The patient underwent left neck exploration, which confirmed left thyroid hemiagenesis and a left inferior parathyroid adenoma. The left inferior parathyroid gland was resected. The patient was discharged home the same day of surgery and has remained normocalcemic for 14 months without evidence of hyperparathyroidism.

Newborn screening for congenital hypothyroidism in very-low-birth-weight babies: the need for a second test

BACKGROUND

Very-low-birth-weight babies (VLBW) with hypothyroidism may show a delayed postnatal rise in thyroid stimulating hormone (TSH), mainly due to immaturity of the hypothalamic-pituitary-thyroid axis. Transient hypothyroidism is prevalent in VLBW babies and some affected babies are considered to need treatment. There is disagreement about whether a second screening test is needed in VLBW babies to detect all cases that need treatment.

METHODS

We included in the study all babies with a birth weight ≤ 1,500 g born in New South Wales and the Australian Capital Territory between January 2006 and December 2008. Newborn screening samples for TSH measurement were taken in the first days of life and again at 1 month. During week 1, a blood-spot TSH level of  ≥20 mIU/L was considered positive, and at 1 month a positive level was  ≥7 mIU/L, and triggered full investigation.

RESULTS

In the cohort of 301,000 babies, 2,313 VLBW babies survived for testing, and 2,117 repeat screening samples were received. Forty-three babies had transient hypothyroidism, with thyroid function normalising before 2 months of age, usually without treatment. Eighteen babies required treatment beyond 2 months of age (1:128 of surviving babies), 16 having had normal TSH results on initial testing, and 12 having levels below 6 mIU/L.

CONCLUSION

Significant hypothyroidism, transient or permanent, but persisting beyond 2 months of age is common in VLBW babies. There is a delayed rise in TSH in some, and secondary screening at 1 month of age detects babies deemed by local paediatric endocrinologists as needing treatment.

Left thyroid hemiagenesis in a patient with primary hyperparathyroidism

The case of a patient with primary hyperparathyroidism with the incidental finding of left thyroid hemiagenesis with isthmus involvement is presented. Thyroid hemiagenesis is a rare congenital abnormality. There have been approximately 310 cases reported in the literature to date. It has been reported as an incidental finding with a wide range of associated pathological conditions. It is important to consider this in patients being prepared for thyroid lobectomy due to the inevitability of postoperative hypothyroidsm. Due to the female predominance of thyroid disease, hemiagenesis was first thought to be more common in women. Left lobe cases accounts for the majority of instances and isthmus is absent in half the cases. Ultrasonography is the diagnostic tool of choice.

Congenital hypothyroidism: etiology

The etiology of congenital hypothyroidism (CH) is important in determining its severity, prognosis, genetic counseling and clinical management.

AIMS

investigate the causes of CH and their severity using serum levels of FreeT4 and TSH.

PATIENTS AND METHODS

243 neonates with CH (61% were girls) diagnosed by the Neonatal Screening Program of Minas Gerais between 1996 and 2003. The thyroid function was assessed through serum FreeT4 and TSH by chemilumiscence. CH etiology was evaluated by ultrasonography, scintigraphy, potassium perchlorate discharge test and serum thyroglobulin levels.

RESULTS

Out of 243 patients, dysgenesis was found in 114 (47%): 3.3% had athyreosis; 0.4% eutopic dysgenetic gland due to maternal use of 131I; 22% ectopic glands (8.6% an isolated ectopic gland and 13% also an eutopic dysgenetic thyroid); 9% eutopic dysgenesis, 8.6% hypoplasia and 3.7% hemiagenesis. Thyroid in situ was found in 129 (52%): 23.5% had iodide organification defect; 3.7% thyroglobulin synthesis defect; 6.2% other 0.4% dyshomonogenesis; iodide transport defect; 1.2% transient CH and 18% a normal gland. Patients with dysgenesis had a more severe CH than those with thyroid in situ (TSH 248.08 vs. 18.17 microIU/mL and FT4 0.32 vs. 0.95 ng/dL, p < 0.001).

CONCLUSIONS

Some cases had more complex dysgenesis, presenting ectopia associated to a dysgenetic eutopic gland. The ultrasound was the best tool to detect the dysgenetic tissue, but the scintigraphy was the most effective in identifying the functioning tissue. The thyroid hormone synthesis defects were found more frequently than expected, but in some cases they could not be defined.

Thyroid hemiagenesis and Graves' disease in a child

Hemiagenesis of the thyroid is a rare malformation and Graves' disease with ophthalmopathy is reported quite rarely in adult patients but is not seen in children. This is a report of an 8-year-old girl with congenital absence of the left thyroid lobe, or hemiagenesis.

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.

Excessive iodine intake and ultrasonographic thyroid abnormalities in schoolchildren

High nutritional levels of iodine may induce a higher prevalence of autoimmune thyroiditis, hypothyroidism, goiter, as well as hyperthyroidism, mostly in the elderly. This study assessed thyroid volume and ultrasonographic abnormalities as well as urinary iodine excretion (UIE) in 964 schoolchildren living in an iodine-sufficient area in southern Brazil. Thyroid volume correlated with age and body surface area in boys and girls. In 76.8% of the children, UIE was above 300 microg/l, with higher levels among boys compared to girls (484.2 microg/l vs 435.3 microg/l, p < 0.001). Thyroid abnormalities detected by ultrasonography included hemiagenesis (0.5%), nodules (0.2%), cysts (0.7%), and hypoechogenicity (11.7%). Goiter was present in 1.9% of the children. Hypoechogenicity, a relevant marker of autoimmune thyroiditis, was the most common abnormality found in our study, and this may be linked to excessive iodine intake.

Papillary carcinoma of a thyroglossal duct cyst in a patient with thyroid hemiagenesis: effectiveness of conservative surgical treatment

OBJECTIVE

To describe a case of thyroglossal duct cyst carcinoma that arose in a patient with right thyroid lobe hemiagenesis.

METHODS

We present the imaging, physical examination findings, treatment, and clinical course of the study patient.

RESULTS

A 35-year-old woman was evaluated for a neck mass that had been present for 6 months and was slowly growing. She reported a previous diagnosis of right hemithyroid agenesis. The patient's preoperative workup included ultrasonography of the neck and head and neck T1- and T2-weighted magnetic resonance imaging, which showed right hemithyroid agenesis and a cystic lesion in the median region of the neck below the hyoid bone. Findings from chest x-rays and thyroid function tests were normal. The patient underwent a modified Sistrunk procedure that included removal of the median portion of the hyoid bone. Histologic findings showed a 2.5-cm thyroglossal duct cyst with a 0.6-cm focus of follicular variant of papillary carcinoma with invasion of the cyst wall. Total thyroidectomy was not performed because of the absence of tumoral invasion of the parenchyma around the thyroglossal duct cyst and because the patient was at low risk for aggressive disease. Cervical ultrasonography examinations were performed 6, 12, and 24 months after treatment, and all findings were normal. Presently, the patient is symptom-free after 4 years of follow-up and has no evidence of disease.

CONCLUSION

Incidentally discovered, well-differentiated thyroid cancer that is confined to a thyroglossal duct cyst in a patient at low risk for aggressive disease can be adequately treated by a modified Sistrunk procedure that includes the median portion of the hyoid bone.

Thyroid isthmus agenesis associated with solitary nodule: A case report

Background

Agenesis of the isthmus associated with nontoxic solitary nodular goiter is a rare congenital anomaly. Imaging data exceptionally has been previously reported in the English language literature.

Case presentation

Preoperative assessment of a 22-year-old white man patient showed an asymptomatic nodule of the thyroid at the left lobe, measuring 2.3 × 1.5 cm in diameter without regional lymphadenopathy. At surgical exploration it was seen an absence of the thyroid isthmus.

Conclusion

Thyroid isthmus agenesis does not cause clinical symptoms by itself and most of the times the diagnosis is incidental due to the existence of other thyroid pathology.

Case of thyroid hemiagenesis and ectopic lingual thyroid presenting as goitre

Objective:

We report an extremely rare case of thyroid hemiagenesis with ectopic lingual thyroid.

Method:

Case report and review of the world literature concerning thyroid hemiagenesis with ectopic lingual thyroid and heredity.

Results:

Ectopic thyroid is an uncommon embryological aberration characterised by the presence of thyroid tissue in a site other than its usual, pretracheal location. The lingual thyroid is the most common manifestation of benign ectopic thyroid tissue, but is still a rare clinical entity. Thyroid hemiagenesis is also a very rare abnormality, in which one thyroid lobe fails to develop. We report a case of left thyroid hemiagenesis and goitre in the right lobe in a 26-year-old woman with an ectopic lingual thyroid.

Conclusion:

To our knowledge, this is the first report in the world literature of thyroid hemiagenesis with ectopic lingual thyroid.

Prevalence of thyroid hemiagenesis in an asymptomatic schoolchildren population

BACKGROUND

Thyroid hemiagenesis is a rare congenital anomaly in which one lobe of thyroid gland fails to develop. Because variations of the prevalence of this anomaly have been reported, the aim of this study was to evaluate the prevalence rate of thyroid hemiagenesis in an apparently normal population from Northern Poland.

METHODS

Ultrasound examination of the thyroid gland was performed in 4004 unselected 7-15-year-old school-children from the seaside zone of Northern Poland.

RESULTS

Two cases of thyroid hemiagenesis were found, both being absence of the left lobe in two girls. Thyroid volumes, adjusted to body surface area, were within normal range; serum thyrotropin, free thyroxine, and free triiodothyronine were within normal limits. Physical examination, abdominal ultrasound, and echocardiography did not show extrathyroidal malformations. Thyroid ultrasound was normal in the girls, parents, and siblings.

CONCLUSIONS

The study showed a 0.05% prevalence of thyroid hemiagenesis in asymptomatic schoolchildren population from iodine-sufficient area of Northern Poland.

Clinical and epidemiological characteristics of thyroid hemiagenesis: ultrasound screening in patients with thyroid disease and normal population

Thyroid hemiagenesis is a rare form of thyroid dysgenesis, in which one thyroid lobe fails to develop. The true prevalence of this rare abnormality is about 0.05-0.2% in normal population. We aimed to determine prevalence of thyroid hemiagenesis in patients with various thyroid disorders and a normal population in a mild to moderate iodine-deficient area. The clinical and thyroid ultrasonography records of 4,833 patients who presented with various thyroid disorders were reviewed. In addition, ultrasonographic data of two large surveys carried out for the community screening of iodine status of children (n = 4,772) and thyroid disorders of adult subjects (n = 2,935) were analyzed. In patients with thyroid disorders, we found 12 cases with thyroid hemiagenesis (0.25%). Thyroid hemiagenesis was due to the agenesis of the left lobe in all cases. The underlying thyroid diseases were Hashimoto's thyroiditis (n = 4), euthyroid multinodular goiter (n = 4), and toxic adenoma (n = 1). Three subjects have no underlying thyroid disease. In ultrasonography screening of normal population, altogether, the absence of the left lobe was detected in only two cases, indicating a true prevalence of thyroid hemiagenesis of 0.025%. None of the reviewed patients had thyroid dysfunction. Our community-based data is in accordance with previous studies in terms of prevalence and male-to-female ratio.

Primary Hyperparathyroidism with Thyroid Hemiagenesis

Thyroid hemiagenesis is a very rare anomaly. We herein report a case with right thyroid lobe agenesis, which was incidentally found during the assessment of primary hyperparathyroidism. A 42-year-old male presenting with urinary lithiasis was suspected of having primary hyperparathyroidism, and had elevated levels of both serum calcium and intact parathyroid hormone. Both computed tomography and ultrasonography demonstrated the absence of right thyroid lobe and a mass of 1 cm in diameter at the left lower pole of the thyroid. The patient underwent lower left parathyroidectomy, which confirmed the right thyroid hemiagenesis, as well as the absence of both upper and lower right parathyroid glands. The resected left lower parathyroid gland was pathologically diagnosed as adenoma. The postoperative course was favourable and he was discharged on the 2nd day after surgery, without complications.

The 22q11 deletion syndrome candidate gene Tbx1 determines thyroid size and positioning

Thyroid dysgenesis is the major cause of congenital hypothyroidism in humans. The underlying molecular mechanism is in most cases unknown, but the frequent co-incidence of cardiac anomalies suggests that the thyroid morphogenetic process may depend on proper cardiovascular development. The T-box transcription factor TBX1, which is the most probable gene for the 22q11 deletion syndrome (22q11DS/DiGeorge syndrome/velo-cardio-facial syndrome), has emerged as a central player in the coordinated formation of organs and tissues derived from the pharyngeal apparatus and the adjacent secondary heart field from which the cardiac outflow tract derives. Here, we show that Tbx1 impacts greatly on the developing thyroid gland, although it cannot be detected in the thyroid primordium at any embryonic stage. Specifically, in Tbx1-/- mice, the downward translocation of Titf1/Nkx2.1-expressing thyroid progenitor cells is much delayed. In late mutant embryos, the thyroid fails to form symmetric lobes but persists as a single mass approximately one-fourth of the normal size. The hypoplastic gland mostly attains a unilateral position resembling thyroid hemiagenesis. The data further suggest that failure of the thyroid primordium to re-establish contact with the aortic sac is a key abnormality preventing normal growth of the midline anlage along the third pharyngeal arch arteries. In normal development, this interaction may be facilitated by Tbx1-expressing mesenchyme filling the gap between the pharyngeal endoderm and the detached thyroid primordium. The findings indicate that Tbx1 regulates intermediate steps of thyroid development by a non-cell-autonomous mechanism. Thyroid dysgenesis related to Tbx1 inactivation may explain an overrepresentation of hypothyroidism occurring in patients with the 22q11DS.

A mouse model demonstrates a multigenic origin of congenital hypothyroidism

Congenital hypothyroidism with thyroid dysgenesis (TD) is a frequent human condition characterized by elevated levels of TSH in response to reduced thyroid hormone levels. Congenital hypothyroidism is a genetically heterogeneous disease. In the majority of cases studied, no causative mutations have been identified and very often the disease does not show a Mendelian transmission. However, in approximately 5% of cases, it can be a consequence of mutations in genes encoding the TSH receptor or the transcription factors TITF1, FOXE1, or PAX8. We report here that in mouse models, the combination of partial deficiencies in the Titf1 and Pax8 genes results in an overt TD phenotype that is absent in either of the singly deficient, heterozygous mice. The disease is characterized by a small thyroid gland, elevated levels of TSH, reduced thyroglobulin biosynthesis, and high occurrence of hemiagenesis. The observed phenotype is strain specific, and the pattern of transmission indicates that at least two other genes, in addition to Titf1 and Pax8, are necessary to generate the condition. These results show that TD can be of multigenic origin in mice and strongly suggest that a similar pathogenic mechanism may be observed in humans.

Thyroid hemiagenesis is a rare variant of thyroid dysgenesis with a familial component but without Pax8 mutations in a cohort of 22 cases

Thyroid hemiagenesis is a rare form of thyroid dysgenesis of which some familial cases have been reported, including one associated with a heterozygous mutation in the Pax8 gene. However, the physiopathology remains not well known. The objectives of this study were 1) to describe the clinical features, 2) to look for familial clustering, and 3) to search for Pax8 mutations in a relatively large cohort of affected patients. A family history of thyroid dysgenesis was found in nine patients (40%), whose affected relatives had ectopic thyroid (n = 4), athyreosis (n = 1), thyroid hemiagenesis (n = 2), or thyroglossal duct cysts (n = 2). Screening for Pax8 mutations identified abnormal migration profiles by SSCP analysis in 3 patients, but direct sequencing did not show coding region mutations in any of the 22 patients. In conclusion, this study provides the first evidence that thyroid hemiagenesis can occur as a familial disorder associated with any form of thyroid dysgenesis. This finding supports both a common underlying mechanism to the various abnormalities in thyroid development and a role for genetic factors; however, our results from Pax8 analysis suggest that this gene may not be a key factor.

Thyroid hemiagenesis: a report of three cases and review of the literature

Thyroid hemiagenesis resulting from the failure of embryologic development of one thyroidal lobe is a very rare anomaly. It is usually incidentally discovered during the investigation of accompanying thyroid disorders. Here we report three cases with right lobe agenesis in two patients and left lobe agenesis in one patient. Two of them were hyperthyroid, while the other euthyroid patient had a thyroid mass.

Thyroid hemiagenesis and incidentally discovered papillary thyroid cancer: case report and review of the literature

Thyroid hemiagenesis (TH) is a rare congenital abnormality in which one thyroid lobe fails to develop. Its prevalence is uncertain, because the absence of one thyroid lobe does not usually cause clinical symptoms. The detection of TH is usually incidental when the evaluation of other thyroid disorders is requested. It is more frequently found in female than in male patients (3:1 ratio) and in the left lobe compared to the right lobe. We report the case of a 54-yr-old man, presenting with a large multinodular right-sided goiter, with mediastinal extension and dysphagia. Thyroid scan and ultrasound study showed the absence of the left lobe. The patient underwent surgery for compressive symptoms, and the operation confirmed the absence of the left lobe. Histological examination demonstrated a multi-nodular goiter with papillary carcinoma. To our knowledge, this case represents the first reported case of association between TH and papillary thyroid carcinoma in a male patient, and the second in which the tumor arose in the right lobe.

Thyroid hemiagenesis with postpartum silent thyroiditis

A 28-year-old woman with thyroid hemiagenesis, who had been diagnosed as having Graves' disease, became pregnant during the course of methimazole treatment. The treatment was terminated in the second trimester. She delivered a normal infant at full term. She became thyrotoxic 3 months after the delivery, hypothyroid 6 months after the delivery, and finally euthyroid 11 months after the delivery without undergoing any treatment. This clinical course indicates that she developed silent thyroiditis after the delivery. A diagnosis of thyroid hemiagenesis was made on the basis of ultrasonography of the thyroid and 99mTc-pertechnetate thyroid scintiscan.

Thyroid hemiagenesis associated with Graves' disease and Graves' ophthalmopathy: case report

Failure of embryologic development of a lobe of the thyroid gland is a rare anomaly. Usually, this condition is diagnosed when there are some other pathologic conditions in the gland and is often found when a patient presents with a thyroid nodule, which in reality is compensatory hypertrophy of the side that is present, therefore appearing as a nodule. A variety of pathological conditions occur in the remaining thyroid tissue in association with this rare anomaly such as adenoma, carcinoma, subacute thyroiditis, colloid nodule, Graves' disease, simple goiter, and Hashimoto thyroiditis. Association of Graves' disease with ophthalmopathy and thyroid hemiagenesis is quite rare and very few cases are reported in the literature. We report a 29-year-old female presented as Graves' disease and Graves' ophthalmopathy with left lobe hemiagenesis of the thyroid gland.

Sonographically guided percutaneous ethanol treatment of a symptomatic complex nodule with a large cystic component in a patient with thyroid hemiagenesis

Thyroid hemiagenesis is a rare anomaly that is usually discovered incidentally during the evaluation of unrelated thyroid disorders. We present the case of a patient with hemiagenesis of the left thyroid lobe and a large, recurrent, symptomatic complex nodule with a large cystic component that occupied most of the right lobe. She had previously undergone multiple unsuccessful aspirations of the cyst. The patient was successfully treated with an intranodular injection of ethanol under sonographic guidance. The success of this procedure resulted in the resolution of symptoms and avoidance of surgical resection of the right lobe, with resulting hypothyroidism. We recommend that ethanol injections be considered for treatment of symptomatic cystic or benign solid nodules in patients with thyroid hemiagenesis and in those who have undergone hemithyroidectomy and have symptomatic nodules.

Causes of appearance of scintigraphic hot areas on thyroid scintigraphy analyzed with clinical features and comparative ultrasonographic findings

This study was done retrospectively to analyze the ultrasonographic (US) findings in thyroid scintigraphic hot areas (HA). Three-thousand, eight-hundred and thirty-nine consecutive patients who underwent 99mTc-pertechnetate (n = 3435) or 123I (n = 457) scintigraphy were analyzed. HA were regarded as present when the tracer concentration was greater than the remaining thyroid tissue, or when hemilobar uptake was observed. High-resolution US examinations were performed with a real-time electronic linear scanner with a 7.5 or 10 MHz transducer. One hundred and four (2.7%) were found to be scintigraphic HA (n = 120). US revealed a nodular lesion or well-demarcated thyroid tissue corresponding to the HA in 94 areas (78.4%, Category 1), an ill-defined region with different echogenicity in 13 areas (10.8%, Category 2), and no correlating lesion in 13 areas (10.8%, Category 3). These 104 patients included 43 with adenomatous goiter (59 areas), 33 with adenoma, 11 with Hashimoto's thyroiditis, 5 with primary thyroid cancer, 4 with euthyroid ophthalmic Graves' disease (EOG), 3 with hemilobar atrophy or hypogenesis, 2 with hemilobar agenesis, 2 with hypothyroidism with blocking-type TSH-receptor antibodies (TSHRAb), I with acute suppurative thyroiditis. Among the 59 adenomatous nodules and 33 adenomas, 51 (86.4%) and 32 (97.0%), respectively, belonged to Category 1. A solitary toxic nodule was significantly larger and occurs more often in older patients than in younger patients. On the other hand, all 17 patients with known autoimmune thyroid diseases including Hashimoto's thyroiditis, EOG and hypothyroidism with blocking TSHRAb belonged to Category 2 or 3. Possible underlying mechanisms are 1) hyperfunctioning tumors or nodules, 2) localized functioning thyroid tissue freed from autoimmune destruction, inflammation or tumor invasion, 3) congenital abnormality, 4) clusters of hyperactive follicular cells caused by long-term TSH and/or TSHRAb stimulation, 5) asymmetry, etc. Scintigraphic HA are observed in patients with various thyroid diseases and high-resolution US appears to be helpful clinically for the differential diagnosis of the above mentioned disorders.