|Year : 2017 | Volume
| Issue : 2 | Page : 131-133
Lingual thyroid: A rare anomaly
Banyameen Iqbal1, Iqra Mushtaq2
1 Department of Pathology, Dr. DY Patil Medical College, Hospital and Research Centre, Pune, Maharashtra, India
2 Department of Ophthalmology, Dr. DY Patil Medical College, Hospital and Research Centre, Pune, Maharashtra, India
|Date of Web Publication||20-Apr-2017|
Department of Pathology, Dr. DY Patil Medical College, Hospital and Research Center, Pimpri, Pune , Maharashtra
Source of Support: None, Conflict of Interest: None
Lingual thyroid (LT) is a rare developmental anomaly originating from aberrant embryogenesis during the passage of the thyroid gland through the neck. LT has an incidence of one in 3,000, with an overall prevalence of one in 100,000. Female to male ratio ranges from 4:1 to 7:1.
Clinical presentation is varying, more related to oropharyngeal obstruction, causing mild to severe dysphagia and/or upper airway obstruction, dysphonia, and sleep apnea. Up to 70% of patients with LT have hypothyroidism. Surgery is the treatment of choice in symptomatic cases. We, hereby, report a case of a 16-year-old girl who presented with a midline swelling at the base of the tongue, was hypothyroid, and on oral thyroxine. The swelling was surgically removed and was diagnosed to be LT. The significance of reporting this case is that it should be recognized and treated at the earliest because of the ill effects of hypothyroidism associated with it.
Keywords: Ectopic thyroid, lingual thyroid, midline neck swelling
|How to cite this article:|
Iqbal B, Mushtaq I. Lingual thyroid: A rare anomaly. J Med Soc 2017;31:131-3
| Introduction|| |
The thyroid gland is one of the largest endocrine glands in the body; it lies approximately at the same level as the cricoid cartilage. Ectopic thyroid tissue had been found from the tongue to the diaphragm. Lingual thyroid (LT) is a rare developmental anomaly originating from aberrant embryogenesis during the passage of the thyroid gland through the neck. It has a reported incidence of one in 3,000 of all the thyroid cases seen with an overall prevalence of one in 100,000, with female to male ratio ranging from 4:1 to 7:1. Of all ectopic thyroids, 90% are found to be LTs. The pathogenesis of LT is unclear; some authors have postulated that maternal antithyroid immunoglobulins may impair gland descent during early fetal life.
| Case Report|| |
We present a case of a 16-year-old girl who came to the outpatient department (OPD) of our hospital with complaints of progressive dysphagia to solid foods since childhood. She did not have any significant history. On examination, a midline neck swelling of 3.5 cm × 2.5 cm was noted. The swelling was smooth and rubbery, present at the base of the tongue. Neck examination did not reveal any palpable thyroid or cervical lymphadenopathy. Ultrasonography (USG) of the neck showed the absence of the thyroid gland. Computed tomography (CT) scan showed a well-defined hyperdense (100–150 HU) lesion in the region of the posterior one-third of the tongue measuring approximately 4 cm × 3 cm. The margins of the lesion showed lobulations and contural bulge. Magnetic resonance imaging (MRI) of the neck showed well-defined mixed signal intensity mass at the posterior aspect of the tongue showing heterogeneous posterior contrast enhancement and narrowing of the oropharynx. Radionuclide scanning using 99m Technetium pertechnetate could not be done, because the patient was reluctant considering the cost factor. Thyroid profile was within normal limits as she was taking thyroxine supplements for the last 6 months. Other hematological investigations were within normal limits. The provisional diagnosis of LT was made and suppression treatment with thyroid hormone was given, followed by surgical resection of the gland via a transoral approach under general anesthesia. It was sent to histopathology for confirmation. Histopathology study revealed a nonencapsulated mass measuring 3.5 cm × 2.5 cm. The cut surface showed numerous colloid filled cystic spaces [Figure 1]. On microscopy, it showed normal thyroid follicles of varying sizes filled with colloid and extending between muscle fibers; a few sections showed normal salivary glands as well [Figure 2]. The patient was discharged after a few days and was followed for a period of 6 months after surgery and the postoperative period was uneventful. The patient was put on oral thyroxine and advised to follow-up with endocrinology OPD.
|Figure 1: Gross figure showing the cut surface of lingual thyroid (LT) and numerous colloid filled cystic spaces|
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|Figure 2: Photomicrograph showing normal thyroid follicles of varying sizes filled with colloid. Lower part of the figure shows a collection of salivary glands [H and E, ×200]|
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| Discussion|| |
LT is defined as the presence of thyroid tissue in the midline at the base of the tongue anywhere between the circumvallate papillae and the epiglottis because of failure of normal thyroid tissue to descend from the foramen cecum area of the tongue base, resulting in a midline mass at the base of the tongue. Dual ectopic thyroid has been described, even with the thyroid gland, in a normal location. Hickmann recorded the first case of LT in 1869. Montgomery stressed that for a condition to be branded as LT, thyroid follicles should be demonstrated histopathologically in tissues sampled from the lesion. Any functioning thyroid tissue found outside of the normal thyroid location is termed as ectopic thyroid tissue. Although, it is usually found along the normal path of development, ectopic tissue has been noted in the mediastinum, heart, esophagus, and diaphragm as well. Clinical presentation is varying, more related to oropharyngeal obstruction, causing mild to severe dysphagia and/or upper airway obstruction, dysphonia, and sleep apnea. Stridor is most common in neonates. The ectopic thyroid secretions are not adequate to maintain a euthyroid state. Up to 70% of patients with LT have hypothyroidism and 10% suffer from cretinism. Diagnosis depends on finding thyroid tissue at the base of the tongue with the absence of normally located gland. CT and MRI are helpful in diagnosing the lesion; however, nuclear scans are better to demonstrate the location of ectopic glands. Radionuclide scanning is done using 99m Technetium pertechnetate and lateral/oblique views are additionally taken for better localization. Management of LT is still not fully defined. No treatment is required when the LT is asymptomatic and the patient is in a euthyroid state; the patient has to be followed for any complications. In cases of symptomatic patients, before surgical excision, exogenous thyroid hormone should be tried first in order to decrease the size of the gland. Patients lacking thyroid tissue in the neck, the LT can be excised and autotransplanted to the muscles of the neck. In patients with obstructive symptoms, Iodine-131 ablation of the ectopic thyroid tissue has proven successful and may be advantageous than surgery. In our patient, elective surgery was done after suppression therapy. Additionally, levothyroxine therapy was initiated after surgical excision. The patient was followed for a period of 6 months after surgery which were uneventful. The patient still attends the medical OPD regularly and is regularly followed-up.
| Conclusion|| |
LT is a rare developmental anomaly whose treatment is still not fully prescribed. However, if the condition is asymptomatic, no surgical intervention is needed; only thyroid levels should be monitored. If the condition is symptomatic, surgical intervention is required and evaluation of thyroid function is needed both before and after surgery due to the risk of postsurgical hypothyroidism. The importance of reporting this case is to make the clinicians/surgeons aware of its early detection and treatment because of the risks of hypothyroidism associated with it.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]