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 Table of Contents     
CASE REPORT
Year : 2014  |  Volume : 29  |  Issue : 2  |  Page : 105-107  

A case of dual ectopy thyroid along the thyroglossal tract demonstrated on 99mTc-Pertechnatate hybrid single photon emission computed tomography/computed tomography


Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi, India

Date of Web Publication9-Apr-2014

Correspondence Address:
Madhavi Tripathi
Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi - 110 029
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0972-3919.130300

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   Abstract 

Ectopic thyroid tissue (ETT) refers to the presence of thyroid tissue in locations other than the normal anterior neck region between the second and fourth tracheal cartilages. Multiple ectopia of the thyroid is extremely rare. Here we report a case of 10-year-old girl with anterior midline neck swelling and hypothyroidism with dual ectopia of thyroid gland without orthotopic thyroid gland. Planar 99 m-technetium pertechnatate scan identified ETT corresponding to the palpable neck swelling. Single photon emission computed tomography/computed tomography (SPECT/CT) demonstrated ETT in two locations, one corresponding to the palpable mass and another in the in the sublingual location. This case thus demonstrates the important role of hybrid SPECT/CT in the identification of dual ectopia along the thyroglossal tract.

Keywords: Dual ectopy, ectopic thyroid, single photon emission computed tomography/computed tomography, thyroglossal tract


How to cite this article:
Agarwal KK, Karunanithi S, Jain S, Tripathi M. A case of dual ectopy thyroid along the thyroglossal tract demonstrated on 99mTc-Pertechnatate hybrid single photon emission computed tomography/computed tomography. Indian J Nucl Med 2014;29:105-7

How to cite this URL:
Agarwal KK, Karunanithi S, Jain S, Tripathi M. A case of dual ectopy thyroid along the thyroglossal tract demonstrated on 99mTc-Pertechnatate hybrid single photon emission computed tomography/computed tomography. Indian J Nucl Med [serial online] 2014 [cited 2019 Dec 9];29:105-7. Available from: http://www.ijnm.in/text.asp?2014/29/2/105/130300


   Introduction Top


Ectopic thyroid is a developmental anomaly of the thyroid gland in which thyroid tissue is present at sites other than its normal location in the neck. [1] It is usually uncommon to have multiple locations of ectopic thyroid tissue (ETT) present simultaneously. [2] Prevalence of thyroid ectopia is approximately 1/100,000-300,000 people. Though ETT can manifest at any age it is mostly noted at adolescence. About 65-80% of cases manifesting with ETT are females. Lingual thyroid is the most common ectopic location for the thyroid accounting for 90% of cases. It is very rare to have two ectopic foci of thyroid tissue simultaneously and only a very few cases of dual ectopy have been reported in the world literature. We report a case of dual thyroid ectopy, wherein 99 m-technetium ( 99m Tc) pertechnatate hybrid single-photon emission computed tomography/computed tomography (SPECT/CT) played an important role in demonstrating multiple ectopia of the thyroid gland. [3],[4],[5],[6]


   Case Report Top


The present case report is about a 10-year-old girl who presented with anterior midline neck swelling since 6 months, which was gradually increasing in size. On evaluation, she was found to have hypothyroidism without evidence of growth retardation. On local examination, a swelling 2 × 2 cm size, cystic, well-defined with a smooth surface neither compressible nor reducible was palpated just below the hyoid bone, which was moving up with protrusion of tongue and with deglutition, but was not trans-illuminant. Serum biochemistry revealed T3 = 86 ng/dL (normal, 70-200 ng/dL), T4 = 4.3 μg/dL (normal, 4.5-12.5 μg/dL) and thyroid-stimulating hormone level of 27 μIU/mL (normal, 0.5-4.7 μIU/mL). With a provisional diagnosis of sub-hyoid thyroglossal cyst, patient was referred for a technetium thyroid scan to rule out functioning thyroid tissue in the cyst. 99m Tc-pertechnatate thyroid scan revealed a midline focus of tracer uptake corresponding to the palpable neck swelling suggestive of ectopic functioning thyroid tissue. No tracer uptake was noted in the region of the thyroid bed. In addition, a small linear streak of tracer activity was seen to extend superiorly [Figure 1] from the ETT in the neck. SPECT/CT of the neck revealed ETT on the right side of the thyroid cartilage, in the sub-hyoid location; in addition to this another ectopic rest of thyroid tissue was noted in the midline floor of the mouth. Tracer was also seen to extend along a tract, which was well-appreciated on sagittal section [Figure 2]. Patient was started on thyroid supplementation therapy.
Figure 1: 99m-technetium-pertechnatate thyroid scan anterior (a) and lateral (b) view revealing a midline focus of tracer uptake corresponding to the palpable neck swelling suggestive of ectopic functioning thyroid tissue. No tracer uptake was noted in the region of the thyroid bed. In addition, a small linear streak of tracer activity was seen to extend superiorly (a-arrow)

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Figure 2: Computed tomography (CT) and hybrid single photon emission computed tomography/CT images of the neck revealing ectopic thyroid tissue on the right side of the thyroid cartilage, in the sub-hyoid location (a and b; arrow) and in the midline floor of the mouth (c and d; broken arrow). Furthermore, tracer was seen to extend along a tract which was well appreciated in sagittal images (e and f)

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   Discussion Top


The thyroid gland develops from the foregut. It descends to its normal cervical position by a circuitous route. Its original position is marked by the foramen caecum at the junction of anterior two-thirds and posterior one-third of the tongue. An evagination appears between the first and second pharyngeal pouch at 4 weeks of gestational age which lengthens to form a tube and descends inferiorly and anteriorly to pass anterior to the hyoid bone and forms the lateral lobes of the thyroid. The pathway from the pharynx to the anterior neck is marked by the thyroglossal duct. [7] It is very unusual for multiple ectopic thyroids rests to be present simultaneously. Very few cases of multiple thyroid ectopia have been published. [8],[9],[10] Hybrid SPECT/CT may be useful in accurate localization of ectopic thyroid rests and to differentiate from other causes of midline cervical masses.

In our case report, planar thyroid scintigraphy showed single ectopic thyroid at the sub-hyoid location but on hybrid SPECT/CT, we found dual ectopia along the thyroglossal tract. In evaluating thyroid ectopy, SPECT/CT may thus have an incremental value over planer scintigraphy for accurate localization of ectopic thyroid rests which may influence patient management.

 
   References Top

1.Kumar Choudhury B, Kaimal Saikia U, Sarma D, Saikia M, Dutta Choudhury S, Barua S, et al. Dual ectopic thyroid with normally located thyroid: A case report. J Thyroid Res 2011;2011:159703.  Back to cited text no. 1
    
2.Chawla M, Kumar R, Malhotra A. Dual ectopic thyroid: Case series and review of the literature. Clin Nucl Med 2007;32:1-5.  Back to cited text no. 2
    
3.Santhosh S, Mittal BR, Kamaleshwaran KK, Parghane R, Bhattacharya A, Singh B. Scintigraphic demonstration of ectopic thyroid tissue in a thyroglossal duct cyst in the presence of a normal thyroid. Clin Nucl Med 2011;36:1142-3.  Back to cited text no. 3
    
4.Manohar K, Bhattacharya A, Kashyap R, Kamaleshwaran KK, Mittal BR. Concurrent sublingual thyroid and thyroglossal cyst with functioning thyroid tissue in the absence of an orthotopic thyroid gland. Jpn J Radiol 2010;28:552-4.  Back to cited text no. 4
[PUBMED]    
5.Harisankar CN. Dual ectopic thyroid in the presence of atrophic orthotopic thyroid gland in a patient with acquired hypothyroidism: Evaluation with hybrid single-photon emission computed tomography/computed tomography. Indian J Nucl Med 2013;28:26-7.  Back to cited text no. 5
[PUBMED]  Medknow Journal  
6.Harisankar CN, Preethi GR, George M. Hybrid SPECT/CT evaluation of dual ectopia of thyroid in the absence of orthotopic thyroid gland. Clin Nucl Med 2012;37:602-3.  Back to cited text no. 6
    
7.Jain A, Pathak S. Rare developmental abnormalities of thyroid gland, especially multiple ectopia: A review and our experience. Indian J Nucl Med 2010;25:143-6.  Back to cited text no. 7
[PUBMED]  Medknow Journal  
8.Abellán Galiana P, Cámara Gómez R, Campos Alborg V, Rivas Sánchez A, Salom Fuster JV, Muñoz Gómez C. Dual ectopic thyroid: Subclinical hypothyroidism after extirpation of a submaxillary mass. Rev Esp Med Nucl 2009;28:26-9.  Back to cited text no. 8
    
9.Sood A, Sood V, Sharma DR, Seam RK, Kumar R. Thyroid scintigraphy in detecting dual ectopic thyroid: A review. Eur J Nucl Med Mol Imaging 2008;35:843-6.  Back to cited text no. 9
[PUBMED]    
10.Basu S, Nair N. Dual ectopic thyroid. Indian Pediatr 2006;43:741.  Back to cited text no. 10
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