Thyroid hemiagenesis associated with medullary or papillary carcinoma: report of cases

Right thyroid lobe agenesis and left thyroid colloid benign nodule discovered incidentally in female with breast carcinoma receiving chemotherapy for multiple metastases: Case report and review of the literature

INTRODUCTION AND IMPORTANCE

Thyroid hemiagenesis (THA) is the failure of embryologic development of a lobe of the thyroid gland and is a rare anomaly of uncertain incidence. The left lobe is more commonly absent than the right lobe. It is discovered incidentally during investigations.

CASE PRESENTATION

A 48 year old Egyptian female presented at the thyroid surgery clinic at our institution to follow up after a nodule left thyroid lobe accidently discovered on positron emission tomography (PET) scan undertaken to follow up on bone metastasis of breast cancer which was surgically removed about 14 years ago.

CLINICAL DISCUSSION

The patient looked clinically well with no scar in the anterior of the neck, no palpable thyroid nodules, and no lymphadenopathy. Ultrasound imaging of the neck revealed absent right thyroid lobe tissue and a nodule was noted at the upper pole of the left thyroid. Laboratory tests unremarkable, with TSH (2.14 mIU/L), and FT4 (12.4 pmol/L) within normal range. Fine needle aspiration and cytology of the thyroid nodule revealed atypia of undetermined significance.

CONCLUSION

THA is rare and right THA is even rarer. It is usually asymptomatic, and diagnosis is mostly incidental while investigating symptoms due to pathology of the other thyroid lobe or any of the parathyroid glands. In much rarer circumstances, right THA might be discovered when investigating conditions not related to the thyroid or parathyroid glands years after the initial pathology as in the current case. Etiology is inconclusive but genetic factors could play a role. No treatment is required if no symptoms are present.

Thyroid Scintigraphy of a Rare Case of Left Thyroid Lobe Hemiagenesis With Subacute Thyroiditis

ABSTRACT

Thyroid hemiagenesis is a rare developmental anomaly. Patients with thyroid hemiagenesis have higher incidence of coexisting thyroid disorders in the remaining lobe. We present a rare case of a 21-year-old woman with subclinical hyperthyroidism incidentally found to have thyroid hemiagenesis on thyroid 123I-Na scan, which is confirmed on thyroid ultrasound. On scintigraphy, only the right lobe showed activity. Thyroid ultrasound demonstrated that the right lobe was normal without any nodule. The left lobe was not visualized. This patient's thyroid uptake and scan also revealed low uptake in the remaining right thyroid lobe in keeping with subacute thyroiditis.

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.

Thyroid hemiagenesis with primary hyperparathyroidism or papillary thyroid carcinoma: A report of two cases and literature review

The combination of TH and PHPT or PTC is extremely rare. A better comprehension of the normal anatomy of the thyroid gland and its variations, congenital anomalies, and related pathologies is essential for safe surgical intervention.

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 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.

Thyroid Hemiagenesis Associated with Hyperthyroidism

Thyroid hemiagenesis (TH), very rare congenital anomaly, is generally asymptomatic. We report two cases of TH with hyperthyroidism. Case One. The patient presented with signs and symptoms of thyrotoxicosis. Physical examination revealed asymmetric nodular goitre at right lobe. Biochemical analysis revealed the diagnosis of hyperthyroidism. Ultrasound showed multinodular hypertrophy in the right lobe and absence of the left lobe. Nuclear scan, confirming absence of the left lobe, showed hot nodules in the right one. The diagnosis was toxic multinodular goitre. Case Two. The thyroid was not palpable in this patient presented with signs and symptoms of thyrotoxicosis. Biochemical analysis revealed the diagnosis of autoimmune thyrotoxicosis. Ultrasound showed mild diffuse hyperplasia of the right lobe and agenesis of the left lobe. Nuclear scan, confirming absence of the left lobe, showed increasing diffuse uptake of radiotracer in the right one. The diagnosis was Graves' disease in this patient. After antithyroid medication, the patients were surgically treated with total excision of the thyroid tissue. TH is sometimes associated with disorders of the thyroid. Hyperthyroidism makes TH cases symptomatic. During evaluation of patients, ultrasound and nuclear scan usually report agenesis of one lobe and establish the diagnosis of TH. The surgical treatment is total removal of hyperactive tissue and total excision of the remaining lobe.