A rare location of thyroglossal duct cyst in a newborn

Thyroglossal duct cyst of the tongue is a rare entity. Occurrence in the anterior part of the tongue is exceptional. We report in this paper a rare case of thyroglossal cyst of the anterior part of the tongue, discovered in a five-days-old newborn at delivery. Images have shown a cystic mass with homogenous liquid content. A transoral complete resection of the lesion was performed, with no postoperative complication. The histological analysis confirm the diagnosis of lingual thyroglossal duct cyst. There were no recurrence with a follow-up of eight months.


Introduction
Thyroglossal duct cyst (TGDC) represents the most common congenital midline mass. It results from remnant epithelial rests of the thyroid gland during it migration throughout the development from the tongue base [1]. Its location in the tongue is a rare entity, observed in 0.6% to 3% of cases at the base of the tongue [2].
Occurrence in the anterior part of the tongue is exceptional [3].
Symptoms are made of dysphagia, obstruction of upper airways and even death have been reported [4,5]. The thyroglossal duct cyst of the tongue can be confused with others cystic masses ie: ranula, dermoid cyst, monocystic lymphangioma. The radiological investigation (ultrasonography, tomography and magnetic resonance imaging) are very helpful for the diagnosis. However, in some cases we could not be sure of the diagnosis only on the histological analysis of the resected specimen. We report in this paper a case of a neonatal thyroglossal duct cyst of the anterior part of the tongue managed with a transoral resection without complication. The length of disease-free follow-up was of 8 months.

Patient and observation
A five-days-old newborn was referred to our department for an enormous lingual mass discovered at delivery. It was a normal

Discussion
Lingual thyroglossal duct cyst (LTGDC) is a rare location, which occur in 0.3-3% of cases, and it is often interest the posterior third of the tongue [2]. The literature reports few cases of occurrence in the anterior part of the tongue [3]. The TGDC can clinically appear at any age and at any site of the pathway migration of the thyroid from caecum foramen to pyramidal lobe [6]. Untreated, the TGDC can cause an upper airways obstruction that can occasionally leads to fatal asphyxia [4,5]. Effectively, the prenatal diagnosis is possible and the neonatal care and management should be prepared to avoid an eventually a neonatal asphyxia [2]. Images (ultrasonography, CT scan) affirm the cystic nature of the lesion but it can be confused, especially in newborns, with a ranula, bronchogenic cyst, dermoide cyst, lymphangioma, so that MRI should be performed when it is possible [2]. In our case, we have decided not to do an MRI because of additional anaesthesia.
Sistrunk procedure is the gold standard of a TGDC resection with the lowest recurrence level [2]. Meanwhile, some authors have adopted more conservative techniques in management of TGDC of the tongue which leads to less complication [2]. Marsupialization is one of techniques adopted with a high rate of recurrence [2,6].

Bai et al.had treated six of nine patients with LTGDC with a needle
puncture. They observed recurrence in two cases (3). The transoral complete resection without recurrence was reported [2,4,5].
Actually, the transoral robotic system resection of LTGDC seems to be a rather efficient method in order to reduce the rate of complications and hospital stay [1]. In our case, because the lingual cyst was anteriorly located, we have decided to perform a transoral approach after a needle aspiration. We suggest that the resection of the hyoid bone shall be discussed when the lingual thyroglossal cyst is anteriorly located, especially since some authors have published cases of thyroglossal cyst managed without Sistrunk procedure with no cases of recurrence. When the location is the base of the tongue, we think that a cervical approach is justified.

Conclusion
Diagnosis of LTGDC in newborn is not usually evident. Image is essential in order to locate exactly the lesion, MRI when it is possible, is preferred because its sensitivity in soft tissues lesions characterization. Surgical approach depends on the location in the tongue and proximity to the hyoid bone.
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Competing interests
The authors declare no competing interests.