International Journal of Pediatric Otorhinolaryngology Extra
Volume 5, Issue 1 , Pages 5-8, January 2010

Persistent cough in a lethargic child: Watch out for lingual thyroid!

  • Shagufta Wahab

      Affiliations

    • Department of Radiodiagnosis, JNMCH, AMU, Aligarh, India
    • ,
  • Rizwan Ahmad Khan

      Affiliations

    • Division of Paediatric Surgery, JNMCH, AMU, Aligarh, India
    • Corresponding Author InformationCorresponding author at: 4/817-F, Sir Syed Nagar, Nagla Road, Aligarh, UP, India. Tel.: +91 9410210281.
    • ,
  • Ruchi Goyal

      Affiliations

    • Department of Radiodiagnosis, JNMCH, AMU, Aligarh, India

Received 15 October 2008; accepted 9 December 2008. published online 27 May 2009.

Article Outline

Summary 

Lingual thyroid presenting as persistent cough and subclinical hypothyroidism is a rare presentation but recognition is nevertheless important. We present one such case and its successful management.

Keywords: Lingual thyroid, Hypothyroidism, Color Doppler sonography

 

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1. Introduction 

Lingual thyroid is a rare anomaly resulting from migration defect. It has been identified in 10% of the tongues examined in some autopsy series [1]. An ectopic thyroid may become symptomatic when it develops goitorous enlargement due to physiological needs or any other cause. Although clinical examination is often sufficient, imaging is often required. While the role of CT and MRI is well documented, high resolution ultrasound remains the ideal initial investigation of choice, particularly in children as it does not involve ionizing radiation or sedation, is readily available, inexpensive and provides the surgeon with the necessary preoperative information [2].

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2. Case report 

A 12-year-old-female child presented to our out-patient clinic with complaints of cough for the last 1 month. There was no history of lethargy, loss of appetite or excessive weight gain. Further enquiry revealed that there is presence of a slowly increasing mass at the base of tongue for past 1 month. Careful oropharyngeal examination revealed a smooth pinkish mass of size 2cm×2cm fixed at base of tongue and covered with normal mucosa (Fig. 1). There was no palpable swelling in the neck. The results of her routine investigations were normal but thyroid function tests showed marginally low levels of tri-iodothyronine (T3) and thyroxine (T4) and significantly raised values of thyroid stimulating hormone (TSH). High frequency ultrasound examination showed a well-defined hypoechoic solid mass at the base of tongue of size 2.0cm×2.6cm and absence of thyroid tissue in the neck region. On color Doppler examination, blood flow was seen in the mass at the base of tongue (Fig. 2). Thyroid technetium scan revealed a focal area of increased tracer uptake corresponding to the clinically visible swelling (Fig. 3). There was no tracer uptake in the area of normal thyroid gland. The child was put on replacement therapy without any surgical intervention. After 4 weeks of follow up, symptoms disappear and the mass gradually became smaller in size.

  • View full-size image.
  • Fig. 2. 

    Color Doppler of the patient showing a well-defined hypoechoic structure at the base of tongue with blood flow and at the same time absence of normally located thyroid gland in the neck.

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3. Discussion 

Embryologically, the thyroid gland develops as an epithelial outgrowth of the pharyngeal floor at the level of future foramen cecum. It begins to grow downward as the thyroid diverticulum, passing ventral to the developing hyoid bone and cartilages and ultimately lies in front of the second tracheal cartilage ring [3]. The failure of migration of thyroid tissue along the path from ventral floor of pharynx to its normal location and sequestration within the tongue substance leads to the development of lingual thyroid [4]. It occurs in one in 100,000–300,000 persons [5]. Other common sites for ectopic thyroid tissue are sublingual, submandibular, prelaryngeal, tracheal, laterocervical, esophageal and substernal [6], [7]. Most of the cases are asymptomatic and the condition may remain unnoticed until puberty when increased demand for thyroid hormone causes the gland to hypertrophy and cause obstructive symptoms like dysphagia, dysphonia, dyspnoea or cough. Respiratory obstruction and haemorrhage in the mass lesion can become life threatening. Possibility of carcinomatous transformation has been reported in 1–3% of cases [7]. Lingual thyroid usually presents itself as midline nodular mass in base of tongue which may appear bluish red to pure red in color with occasional surface ulcerations. Evaluation in such patients includes thorough head and neck examination with special attention to the base of tongue. Palpation of neck is essential in order to check for presence or absence of thyroid gland. In about 70% of patients with lingual thyroid there is absence of normal thyroid gland [8]. About 14.5–33% of cases show hypothyrodism findings [9], as in our case. Other possibilities that can be considered in a patient presenting with a midline posterior tongue mass includes thyroglossal duct cyst, lymphangioma, hemangioma, lipoma, dermoid cyst, fibroma, lingual cyst or carcinoma [10]. On ultrasonography the surface of the lesion is usually smooth and the echotexture resembled that of normally positioned thyroid gland. CT may offer the advantage of superior spatial delineation and precision to help further characterize these lesions. MRI gives the best topographical information about involved structures [11]. Color Doppler exhibits vascularity in mass lesion which is usually low resistance arterial blood flow [5], [10]. Onishi et al. [12] showed that sonography with color Doppler was more sensitive than MRI for detecting ectopic thyroid tissue. Thyroid scintigraphy is the most definitive noninvasive technique for establishing the diagnosis of thyroid ectopia, and in most instances it can identify all sites of ectopic thyroid tissue [13]. Routine preoperative radioisotope thyroid scanning is advocated because of the concern that the lesion might be ectopic thyroid representing the only functioning thyroid gland in the neck. The excision of this mass might result in permanent hypothyroidism [14]. A euthyroid patient with asymptomatic lingual thyroid should be subjected to regular follow up without adopting any further management measures [15]. In symptomatic patients as was in our case, it has been suggested that all patients should be given thyroxine in sufficient doses to suppress TSH stimulation to minimize risk of goitrous enlargement or malignancy [16]. If the lesion is obstructive, reduction in size should be achieved either by surgery or by radioiodine ablation [17]. Surgical excision may be done via an intraoral approach or externally via median or lateral pharyngotomy which should be followed by either autotransplantation or lifelong postoperative hormone replacement therapy to prevent hypothyroidism as in 70% cases this only functioning thyroid tissue [18]. Radioiodine therapy can cause acute swelling of gland and can worsen obstructive symptoms, thus it is used only when patient is unfit or refuses surgery.

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4. Conclusion 

Although lingual thyroid is a rare entity, its identification is of great significance since it may be the only functional thyroid tissue in the body and also its enlargement can cause serious complications. A complete history, careful physical examination, thoughtful use of preoperative thyroid function tests and imaging modalities should be employed to confirm the diagnosis, to identify the presence of any other functioning thyroid tissue in the neck and defining the anatomical relationships of the gland, particularly when surgical intervention is planned.

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Funding 

None.

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Conflict of interest 

Nothing to declare

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References 

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PII: S1871-4048(08)00082-8

doi:10.1016/j.pedex.2008.12.004

International Journal of Pediatric Otorhinolaryngology Extra
Volume 5, Issue 1 , Pages 5-8, January 2010

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