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 associated with Hurthle cell carcinoma: A case report

Introduction and importance

Thyroid hemiagenesis (TH) is a rare congenital anomaly where one lobe fails to develop, especially more frequently occurs on the left lobe. The exact mechanisms for thyroid morphogenesis remain unclear. In this paper, we report a rare case of right lobe TH associated with Hurthle cell carcinoma.

Case presentation

A 59 years old woman was admitted with a neck lump increasing in size in the last 20 years. There were no symptoms of hyperthyroidism and hypothyroidism. There was a palpable, painless 5 cm mass in the middle of the neck. Initial thyroid ultrasonography (USG) revealed an enlarged left lobe, with hypoechoic lesion with cystic component and calcification (TIRADS 4). However, the right lobe was non-visualized. Fine needle aspiration biopsy result tendency was a malignancy. Hence, isthmolobectomy was conducted. Pathology result was Hurthle cell carcinoma. On the ninth month, USG revealed fibrotic tissue in the right thyroid bed and bilateral lymphadenopathy. Due to discrepancy, the patient was planned for a neck exploration surgery and a right lobe incision. Intraoperatively, the right thyroid was absent. Intraoperative USG also confirmed no right thyroid lobe.

Discussion

Thyroid hemiagenesis can be visualized by using USG due to its practicality and cost effectiveness reasons. Follow up evaluations consisted of systematic monitoring of thyroid morphology and hormonal functions should follow the diagnosis of TH. Neck exploration surgery might need to be performed to clarify any discrepancy and confirm the diagnosis.

Conclusion

TH can be recognized through supporting examination; however, discrepancy may occur.

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History taking and physical examination is mandatory yet might not adequate to diagnose hemiagenesis accompanying thyroid diseases.

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Ultrasonography is easily performed, cost effective, and without any radiation exposure to identify thyroid hemiagenesis

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If discrepancy occur in ultrasonography examination, neck exploration surgery can clarify and confirm the diagnosis.

Compound heterozygous GLI3 variants in siblings with thyroid hemiagenesis

PURPOSE

Thyroid hemiagenesis (THA) is an inborn absence of one thyroid lobe of largely unknown etiopathogenesis, affecting 0.05-0.5% population. The aim of the study was an identification of genetic factors responsible for thyroid maldevelopment in two siblings with THA.

METHODS

We evaluated a three-generation THA family with two sisters presenting the disorder. Proband (Patient II:3) was diagnosed at the age of 45 due to neck asymmetry. Left lobe agenesis and nontoxic multinodular goiter were depicted. Proband's sister (Patient II:6) was euthyroid, showed up at the age of 39 due to neck discomfort and left-sided THA was demonstrated. Affected individuals were subjected to whole-exome sequencing (WES) (Illumina, TruSeq Exome Kit) and all identified variants were evaluated for pathogenicity. Sanger sequencing was used to confirm WES data and check segregation among first-degree relatives.

RESULTS

In both siblings, a compound heterozygous mutations NM_000168.6: c.[2179G>A];[4039C>A] (NP_000159.3: p.[Gly727Arg];[Gln1347Lys]) were identified in the GLI3 gene, affecting exon 14 and 15, respectively. According to the American College of Medical Genetics, variants are classified as of uncertain significance, and were found to be very rare (GnomAD MAF 0.007131 and 0.00003187). The segregation mapping and analysis of relatives indicated causativeness of compound heterozygosity.

CONCLUSIONS

We demonstrated for the first time a unique association of THA phenotype and the presence of compound heterozygous mutations p.[Gly727Arg];[Gln1347Lys] of GLI3 gene in two siblings.

Thyroid Hemiagenesis and Papillary Carcinoma: a Rare Association

A 20-year-old female presented with a slowly growing solitary left thyroid nodule for 1 year. USG and CECT neck showed a 4 × 3 cm solid-cystic nodule in the left lobe of thyroid, with notable absence of the right lobe. FNAC from the nodule was Bethesda V. Operative findings confirmed right thyroid lobe agenesis with corresponding absence of right superior thyroid vessels. The right sided RLN, ESBLN, superior and inferior parathyroids, and inferior thyroid vasculature were in their anatomical positions. She underwent standard left hemithyroidectomy. Histopathological examination revealed follicular variant of papillary carcinoma.

Thyroid Hemiagenesis in a Thyroiditis Prone Mouse Strain

BACKGROUND

Thyroid hemiagenesis, a rare congenital condition detected by ultrasound screening of the neck, is usually not manifested clinically in humans. This condition has been reported in mice with hypothyroidism associated with induced deficiency in paired box 8 and NK2 homeobox 1, sonic hedgehog, or T-box 1. Unexpectedly, we observed thyroid hemiagenesis in NOD.H2^h4 mice, an unusual strain that spontaneously develops iodide enhanced thyroid autoimmunity but remains euthyroid.

OBJECTIVES AND METHODS

First, to compare mice with thyroid hemiagenesis versus bilobed littermates for serum T4, autoantibodies to thyroglobulin (ELISA) and thyroid peroxidase (TPO; flow cytometry with eukaryotic cells expressing mouse TPO), gross anatomy, and thyroid histology; second, to estimate the percentage of mice with thyroid hemiagenesis in the NOD.H2^h4 mice we have studied over 6 years.

RESULTS

Thyroid hemiagenesis was observed in 3 of 1,025 NOD.H2^h4 mice (2 females, 1 male; 0.3$). Two instances of hemiagenesis were in wild-type females and one in a transgenic male expressing the human TSHR A-subunit in the thyroid. Two mice had very large unilobed glands, as in some human cases with this condition. Thyroid lymphocytic infiltration, serum T4, and the levels of thyroid autoantibodies were similar in mice with thyroid hemiagenesis and bilobed littermates.

CONCLUSIONS

Unlike hypothyroidism associated with hemiagenesis in transcription factor knockout mice, hemiagenesis in euthyroid NOD.H2^h4 mice occurs spontaneously and is phenotypically similar to that occasionally observed in humans.

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.

Mutations in proteasome-related genes are associated with thyroid hemiagenesis

PURPOSE

Human thyroid development is a complex and still unexplained process. Thyroid hemiagenesis is a congenital anomaly, where one of the thyroid lobes fails to develop. In the majority of patients with thyroid hemiagenesis, the genetic background remains unknown. The aim of the study was to search for novel genetic contributors to the etiology of thyroid hemiagenesis.

METHODS

A cohort of 34 sporadic patients diagnosed with thyroid hemiagenesis and one three-generation family were subjected to comprehensive genomic examination. Initially, targeted screening of associated transcription factors, known to be linked to thyroid development, was performed. As a next step, genomic examinations were applied using high-resolution microarrays, whereas for the thyroid hemiagenesis family, additionally the whole exome sequencing was performed.

RESULTS

Screening of transcription factors revealed no causative mutations in the studied cohort. Genomic examinations revealed the presence of four recurrent defects (three deletions and one duplication) affecting highly conservative proteasome genes PSMA1, PSMA3, and PSMD3. In a thyroid hemiagenesis family a splice site mutation in a proteasome gene PSMD2 (c.612T > C cDNA.1170T > C, g.3271T > C) was found in both affected mother and daughter.

CONCLUSIONS

Our results shed a new light on etiology of thyroid hemiagenesis, so far suspected to be linked only to mutations in the genes directly involved in the thyroid development. We demonstrated, for the first time, that genomic alterations in proteasome-associated genes co-occur in patients presenting this developmental anomaly.

Congenital thyroid hemiagenesis with thyroid nodules-Role of TI-RADS to prevent long term thyroid replacement therapy

Background

Hemi-agenesis of thyroid is a rare congenital condition with the clinical significance lying only in cases where the remnant tissue is affected by a pathology mandating removal of the gland. Henceforth, the hemi-thyroidectomy technically becomes a total thyroidectomy with a need for long term thyroid replacement therapy.

Case summary

We present a series of three cases noted over a period of two years where preoperative imaging evaluation confirmed the developmental abnormality. Further presence of a thyroid nodule in each of these cases posed a specific clinical situation whereby characterization of nodule appeared mandatory for a rational management involving life-long thyroid replacement therapy due to an ‘apparent total thyroidectomy’, if the remnant gland is removed. Ultrasound TI-RADS is a new system for evidence based sub-classification of thyroid nodules enabling both the surgeon and patient to take a streamlined decision about the overall approach for management.

Conclusion

Prospective nodule characterization based on the thyroid image reporting and data system (TI-RADS), enables the surgeon to decide the treatment strategy sparing the patient of the cost and morbidity associated with long term thyroid replacement therapy.

Complete sternal cleft associated with right clavicular, manubrial, and thyroid hypoplasia, pectus deformity, and spinal anomalies

Sternal cleft anomalies are rare. Associated anomalies include pentalogy of Cantrell and posterior fossa abnormalities, hemangiomas, arteriopathy, cardiac anomalies, eye abnormalities, and sternal defects syndrome. There is only a single report of complete sternal cleft, pectus excavatum, and right clavicular hypoplasia in an adult. Thyroid hemiagenesis is also very rare. To our knowledge, this is the first case of complete sternal cleft, pectus deformity, and right clavicular hypoplasia in a child and the first case with right thyroid hemiagenesis.

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.