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case reports

Indian Pediatr 2013;50: 420-421

Ectopic Thyroid in Presumed Thyroglossal Duct Cyst


Babulreddy hanmayyagari, Mounika guntaka
* and Vinay kumar ravilala**

From the Department of Endocrinology, ESI Hospital, Sanathnagar, * Department of Biochemistry, Prime Hospital, KPHB; and **Department of Radiology, ESI Hospital, Hyderabad; Andhra Pradesh, India.

Correspondence to:  Dr H Babulreddy,  Flat No. 507, Emerald Block, My home jewel, Madinaguda,
Hyderabad 500 049,  Andhra Pradesh, India.

Received: September 10, 2012;
Initial review: October 11, 2012;
Accepted: October 25, 2012.


We report a case of an eight year old female child with a midline neck mass for seven years. Since its early presentation, this midline mass has recently increased in size. A presumptive diagnosis of thyroglossal duct cyst was made clinically & planned for surgery. Preoperative evaluation revealed hypothyroidism, hence she was referred to us for the management of the same prior to excision. On further evaluation 99 Tc-thyroid scan showed that this midline mass was in fact the only functioning thyroid tissue & ultrasonography revealed no thyroid tissue in usual location, therefore no surgery was performed. This case demonstrates the essential role of a thyroid scan and ultrasonography in the preoperative evaluation of a midline neck mass.

Key words: Ectopic thyroid, Thyrogossal duct cyst (TGDC),99 Tc-thyriod scan, Ultrasonography.
 


Ectopic thyroid tissue is a rare developmental abnormality involving aberrant embryogenesis of the thyroid gland during its passage from the floor of the primitive foregut to its final pre-tracheal position. Its prevalence is about 1 per 100000-300000 people, increasing to 1 per 4000–8000 patients with thyroid disease [1,2]. Ectopic thyroid is most common in females, especially in populations of Asian origin [3,4]. It may occur at any age, from 5 months to 40 years, but it is most common at younger ages. We report the course and management of a child with ectopic thyroid which mimicked as thyroglossal duct cyst.

Case Report

An 8-year-old female child presented to our out-patient department with history of midline neck mass first noted at one year of age. Since its early presentation, this midline mass had increased in size, more so in recent past. There was no history of dysphagia, dyspnea, recurrent respiratory tract infections and there was no history suggestive of hypothyroidism or thyrotoxicosis. Patient was evaluated earlier and provisionally diagnosed to have throglossal duct cyst and planned for surgery. Preoperative investigation revealed hypo-thyroidism, so she was referred to our department for the management of hypothyroidism prior to excision.

On examination, the general health condition of child was normal with height of 121cm,weight of 22 kg, patient had pre-pubertal sexual maturity. A midline firm neck swelling 2×2 cm in size in the hyoid region moving with deglutition and protrusion of tongue was noted (Fig. 1). Systemic examination including cardiovascular and gastrointestinal systems were normal.

Fig.1 Showing midline neck swelling.

Routine hematology was normal, bone age was slightly delayed (7 yrs as determined by Greulich and Pyle chart), TSH-35.71 miU/mL (0.3-5.5 mµU/mL), Fine needle aspiration cytology –thyroglossal cyst, thyroid peroxidase antibody 20 U/mL (1-34U/mL). 99 TC -thyroid uptake scan revealed that this midline mass was in fact the only functioning thyroid tissue. Replacement with L-thyroxine 50 mcg/day was started and no surgery was performed. On follow-up, patient is doing well, her TSH was 1.26 miU/mL with slight reduction in the size of the gland.

Discussion

The most common site of ectopic thyroid is a lingual thyroid. The wall of a thyroglossal duct cyst is the second most common site for ectopic thyroid tissue. Up to 1 to 2 percent of patients presenting with what appears to be a thyroglossal duct cust TGDC have an ectopic thyroid gland [5,6]. Ectopic thyroid is mostly asymptomatic, but approximately a third of patients present with hypothyroidism, hyperthyroidism is exceptionally rare. These conditions cause enlargement of the gland thereby obstructive symptoms. With treatment size decreases, but surgical excision may become necessary in some cases.

Although most of the available literature state the incidence of ectopic thyroid tissue in presumed thyroglossal duct cyst is 1-2% [7]. Gupta, et al. [8] reported in their series that when screened by pre-operative ultra sound, this incidence is substantially less. Neverthless to prevent inadvertent removal of only functioning thyroid tissue and subsequent complications, they proposed routine preoperative USG in suspicious thyroglossal duct cyst.

This case demonstrates clinical difficulty in differentiation of ectopic thyroid tissue with a thyroglossal duct cyst. Hence such suspected cases as TGDC should have thyroid function tests, ultrasonography and 99 Tc thyroid scan to locate additional functioning thyroid tissue which avoids subjecting the patient to inappropriate surgery and subsequent sequelae.

Contributors: All authors contributed to the management of case and drafting the paper.

Funding: None; Competing interests: None stated.

References

1. Di Benedetto V. Ectopic thyroid gland in the submandibular region simulating a thyroglossal duct cyst: a case report. J Pediatric Surgery. 1997;32:1745-6.

2. Babazade F, Mortazavi H, Jalalian H, Shahvali E. Thyroid tissue as a submandibular mass: a case report. Journal of Oral Science. 2009;51: 655-7.

3. Gopal RA, Acharya SV, Bandgar T, Menon PS, Marfatia H, Shah NS. Clinical profile of ectopic thyroid in Asian Indians: a single-center experience. Endocrine Practice. 2009;15:322–5.

4. Yoon JS, Won KC, Cho IH, Lee JT, Lee HW. Clinical characteristics of ectopic thyroid in Korea. Thyroid. 2007;17:1117-21.

5. Radkowski D, Arnold J, Healy GB, McGill T, Treves ST, Paltiel H, et al. Thyroglossal duct remnants. Preoperative evaluation and management. Arch Otolaryngol Head Neck Surg. 1991; 117:1378.

6. DeMello DE, Lima JA, Liapis H. Midline cervical cysts in children. Thyroglossal anomalies. Arch Otolaryngol Head Neck Surg. 1987;113:418.

7. Tunkel DE, Domenach EE. Radioisotope scanning of thyroid gland prior to thyroglossal duct cyst excision. Arch Otolaryngol Head Neck Surg. 1998;124:597-9.

8. Gupta P, Maddalozzo J. Preoperative sonography in presumed thyroglossal duct cysts. Arch Otolaryngol Head Neck Surg. 2001;127:200-2.

 

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