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Thyroid Hemiagenesis in a Euthyroid man
P I C T O R I A L E S S A Y
Thyroid Hemiagenesis in a Euthyroid man Lilian Shu-Tin Yeh, Chih-Yuan Wang* We report an unusual case of a 46-year-old man with right thyroid hemiagenesis that was found incidentally on a whole body CT scan performed as a routine health checkup. A 2.0 × 3.5 cm cystic nodule in the left lobe was also found. Thyroid hemiagenesis is a rare anomaly that results from failure of the embryonic development of one thyroid lobe. Surgical intervention for lesions of the remaining lobe should only be performed if there is an absolute indication as the surgery could potentially result in permanent hypothyroidism.
KEY WORDS — euthyroidism, nodular goiter, thyroid hemiagenesis ■ J Med Ultrasound 2010;18(2):79–80 ■
A 47-year-old man with no past medical history underwent a whole body computed tomography scan for a health checkup. Right thyroid hemiagenesis and a 2.0 × 3.5 cm cystic nodule on the left were found. The patient was clinically and biochemically euthyroid; antimicrosomal antibody was negative. Thyroid ultrasound also revealed the absence of the right lobe between the carotid artery and longus colli muscle and a left nodular goiter with cystic change (Fig. 1). The nodule measured 3.03 × 2.27 × 1.39 cm. Fine needle aspiration of the nodule showed a few follicular and Hurthle cells amongst colloid material. This nodule showed no malignant features, and therefore, surgery was not indicated. The patient was regularly followed up with thyroid sonography. There was no family history of thyroid disease. Thyroid hemiagenesis occurs rarely with a prevalence of 0.05–0.2% in the normal pediatric population [1]. It results from failure of the development of
Received: July 10, 2009
one thyroid lobe, usually the left, during embryonic development. The thyroid gland develops at gestational day 16–17 from the endoderm of the floor of the pharynx with some contribution from the lateral pharyngeal pouches. As it develops, it descends along the thyroglossal duct to reach its final location in the neck by week 7 of gestation. During its descent it assumes a bilobate shape. In thyroid hemiagenesis, it is unknown whether it is the descent or the bilobate process that is disrupted. Thyroid hemiagenesis has been reported together with other thyroid malformations in members of the same family, including monozygotic twins and sisters, thus suggesting a genetic component in its pathogenesis [2]. A case report from Taiwan described a 44-year-old woman who had left thyroid hemiagenesis with concurrent Graves’ disease in the contralateral lobe. Review of her family history revealed that her 20-year-old daughter had congenital hypothyroidism due to thyroid agenesis,
Accepted: March 24, 2010
Division of Endocrinology, Department of Internal Medicine, Far-Eastern Memorial Hospital and National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan. *Address correspondence to: Dr. Chih-Yuan Wang, Division of Endocrinology, Department of Internal Medicine, Far-Eastern Memorial Hospital, 21 Nan-Ya Road South, Section 2, Pan-Chiao, Taipei, Taiwan. E-mail: [email protected]
©Elsevier & CTSUM. All rights reserved.
J Med Ultrasound 2010 • Vol 18 • No 2
79
L.S.T. Yeh, C.Y. Wang
A
B CA
T
Right thyroid gland absent
∗
Left thyroid gland
CA
CL CL
∗
Right Left
Fig. 1. Both (A) thyroid ultrasound and (B) computed tomography scan show the absence of the right thyroid lobe. *Cyst. CA = carotid artery; CL = longus colli muscle; T = trachea. two sisters, one with Graves’ disease, and the other with multinodular goiter [3]. Hemiagenesis of the thyroid gland has been described in Shh−/− mice embryos and double heterozygous Titf1+/−, Pax8+/− mice. However, in humans, candidate genes responsible for thyroid hemiagenesis have not yet been described [4]. Because the absence of one thyroid lobe does not usually cause clinical symptoms, detection is usually incidental on imaging when the evaluation of other thyroid disorders are requested; this may also explain the female preponderance of this disorder, as more females seek medical attention for thyroid problems than males as a result of the higher incidence of thyroid disorders in females. Thus, the true incidence of thyroid hemiagenesis in males may be underestimated clinically. Various types of thyroid diseases have been reported in the remaining lobe, and these include Graves’ disease, chronic lymphocytic thyroiditis, subacute thyroiditis, nodular and multinodular goiter, adenoma, and occasionally thyroid carcinoma. Although thyroid hemiagenesis is rare and causes no functional problems, its recognition is especially important when thyroid ablative therapy is a treatment option for lesions in the contralateral lobe. In such cases, ablative therapy should be avoided if possible to preserve thyroid function, as demonstrated in the current case. Therefore, pre-operative differentiation between benign
80
J Med Ultrasound 2010 • Vol 18 • No 2
and malignant nodules in the contralateral lobe is especially important in this group of patients. Preoperative recognition of an absent thyroid lobe also avoids unnecessary contralateral neck exploration, which may increase the risk of parathyroid or recurrent nerve injury. This possibility was illustrated in a case report from Taiwan of a 47-year-old woman with right thyroid hemiagenesis, papillary thyroid cancer and an ectopic prelaryngeal thyroid [5].
References 1. Shabana W, Delange F, Freson M, et al. Prevalence of thyroid hemiagenesis: ultrasound screening in normal children. Eur J Pediatr 2000;159:456–8. 2. Léger J, Marinovic D, Garel C, et al. Thyroid developmental anomalies in first degree relatives of children with congenital hypothyroidism. J Clin Endocrinol Metab 2002;87:575–80. 3. Lee IT, Sheu W H-H, Lin SY. Familial form of thyroid dysgenesis: report of thyroid hemiagenesis with accompanying graves’ disease in a woman whose daughter has thyroid agenesis. Horm Res 2003;59:47–9. 4. Felice M, Lauro R. Thyroid development and its disorders: genetics and molecular mechanisms. Endocr Rev 2004;25:722–46. 5. Huang SM, Chen H-D, Wen TY, et al. Right thyroid hemiagenesis associated with papillary thyroid cancer and an ectopic prelaryngeal thyroid: a case report. J Formos Med Assoc 2002;101:368–71.
Thyroid Hemiagenesis in a Euthyroid man Lilian Shu-Tin Yeh, Chih-Yuan Wang* We report an unusual case of a 46-year-old man with right thyroid hemiagenesis that was found incidentally on a whole body CT scan performed as a routine health checkup. A 2.0 × 3.5 cm cystic nodule in the left lobe was also found. Thyroid hemiagenesis is a rare anomaly that results from failure of the embryonic development of one thyroid lobe. Surgical intervention for lesions of the remaining lobe should only be performed if there is an absolute indication as the surgery could potentially result in permanent hypothyroidism.
KEY WORDS — euthyroidism, nodular goiter, thyroid hemiagenesis ■ J Med Ultrasound 2010;18(2):79–80 ■
A 47-year-old man with no past medical history underwent a whole body computed tomography scan for a health checkup. Right thyroid hemiagenesis and a 2.0 × 3.5 cm cystic nodule on the left were found. The patient was clinically and biochemically euthyroid; antimicrosomal antibody was negative. Thyroid ultrasound also revealed the absence of the right lobe between the carotid artery and longus colli muscle and a left nodular goiter with cystic change (Fig. 1). The nodule measured 3.03 × 2.27 × 1.39 cm. Fine needle aspiration of the nodule showed a few follicular and Hurthle cells amongst colloid material. This nodule showed no malignant features, and therefore, surgery was not indicated. The patient was regularly followed up with thyroid sonography. There was no family history of thyroid disease. Thyroid hemiagenesis occurs rarely with a prevalence of 0.05–0.2% in the normal pediatric population [1]. It results from failure of the development of
Received: July 10, 2009
one thyroid lobe, usually the left, during embryonic development. The thyroid gland develops at gestational day 16–17 from the endoderm of the floor of the pharynx with some contribution from the lateral pharyngeal pouches. As it develops, it descends along the thyroglossal duct to reach its final location in the neck by week 7 of gestation. During its descent it assumes a bilobate shape. In thyroid hemiagenesis, it is unknown whether it is the descent or the bilobate process that is disrupted. Thyroid hemiagenesis has been reported together with other thyroid malformations in members of the same family, including monozygotic twins and sisters, thus suggesting a genetic component in its pathogenesis [2]. A case report from Taiwan described a 44-year-old woman who had left thyroid hemiagenesis with concurrent Graves’ disease in the contralateral lobe. Review of her family history revealed that her 20-year-old daughter had congenital hypothyroidism due to thyroid agenesis,
Accepted: March 24, 2010
Division of Endocrinology, Department of Internal Medicine, Far-Eastern Memorial Hospital and National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan. *Address correspondence to: Dr. Chih-Yuan Wang, Division of Endocrinology, Department of Internal Medicine, Far-Eastern Memorial Hospital, 21 Nan-Ya Road South, Section 2, Pan-Chiao, Taipei, Taiwan. E-mail: [email protected]
©Elsevier & CTSUM. All rights reserved.
J Med Ultrasound 2010 • Vol 18 • No 2
79
L.S.T. Yeh, C.Y. Wang
A
B CA
T
Right thyroid gland absent
∗
Left thyroid gland
CA
CL CL
∗
Right Left
Fig. 1. Both (A) thyroid ultrasound and (B) computed tomography scan show the absence of the right thyroid lobe. *Cyst. CA = carotid artery; CL = longus colli muscle; T = trachea. two sisters, one with Graves’ disease, and the other with multinodular goiter [3]. Hemiagenesis of the thyroid gland has been described in Shh−/− mice embryos and double heterozygous Titf1+/−, Pax8+/− mice. However, in humans, candidate genes responsible for thyroid hemiagenesis have not yet been described [4]. Because the absence of one thyroid lobe does not usually cause clinical symptoms, detection is usually incidental on imaging when the evaluation of other thyroid disorders are requested; this may also explain the female preponderance of this disorder, as more females seek medical attention for thyroid problems than males as a result of the higher incidence of thyroid disorders in females. Thus, the true incidence of thyroid hemiagenesis in males may be underestimated clinically. Various types of thyroid diseases have been reported in the remaining lobe, and these include Graves’ disease, chronic lymphocytic thyroiditis, subacute thyroiditis, nodular and multinodular goiter, adenoma, and occasionally thyroid carcinoma. Although thyroid hemiagenesis is rare and causes no functional problems, its recognition is especially important when thyroid ablative therapy is a treatment option for lesions in the contralateral lobe. In such cases, ablative therapy should be avoided if possible to preserve thyroid function, as demonstrated in the current case. Therefore, pre-operative differentiation between benign
80
J Med Ultrasound 2010 • Vol 18 • No 2
and malignant nodules in the contralateral lobe is especially important in this group of patients. Preoperative recognition of an absent thyroid lobe also avoids unnecessary contralateral neck exploration, which may increase the risk of parathyroid or recurrent nerve injury. This possibility was illustrated in a case report from Taiwan of a 47-year-old woman with right thyroid hemiagenesis, papillary thyroid cancer and an ectopic prelaryngeal thyroid [5].
References 1. Shabana W, Delange F, Freson M, et al. Prevalence of thyroid hemiagenesis: ultrasound screening in normal children. Eur J Pediatr 2000;159:456–8. 2. Léger J, Marinovic D, Garel C, et al. Thyroid developmental anomalies in first degree relatives of children with congenital hypothyroidism. J Clin Endocrinol Metab 2002;87:575–80. 3. Lee IT, Sheu W H-H, Lin SY. Familial form of thyroid dysgenesis: report of thyroid hemiagenesis with accompanying graves’ disease in a woman whose daughter has thyroid agenesis. Horm Res 2003;59:47–9. 4. Felice M, Lauro R. Thyroid development and its disorders: genetics and molecular mechanisms. Endocr Rev 2004;25:722–46. 5. Huang SM, Chen H-D, Wen TY, et al. Right thyroid hemiagenesis associated with papillary thyroid cancer and an ectopic prelaryngeal thyroid: a case report. J Formos Med Assoc 2002;101:368–71.