Management outcome of thyroglossal cyst in a tertiary health center in Southwest Nigeria

Thyroglossal duct cyst is a non-odontogenic congenital developmental cyst. It is predominantly a midline anterior neck swelling in children and total excision of the tracts prevents recurrence. Retrospective hospital record analysis of patients managed with histopathology results of thyroglossal cyst between 2003 and 2018. Comparing outcomes and technique of thyroglossal cyst excision in a resource challenged environment. A total of 37 patients comprising 22(59.5%) males and 15(40.5%) females (M:F 1.4:1) with age range of 13 days to 55 years (median 6 years) were managed. The majority were children less than 10 years of age. They all presented with a fluctuant midline progressive anterior neck swelling, in addition to anterior neck ulcer 1(2.7%), discharging sinuses 3(8.1%) and thyroglossal cyst duct infections, which were managed successfully with antibiotics. Central compartment neck dissection with excision of mid-portion of the hyoid bone was performed in all the patients. Rupture of thyroglossal duct cysts was observed in 7(18.9%) at surgery, but there was no recurrence. Surgical drain was not used and most patients were discharged within 48 hours postoperatively. Thyroglossal duct cyst was confirmed at histology without any evidence of mitotic changes. There was no recurrence for the Sistrunk's procedure in all specialties. The modification of the Sistrunk's procedure with mid-anterior neck dissection is effective in excising a thyroglossal duct cyst, hence preventing recurrence. Non-usage of wound drains and short hospital stay are cost effective.


Introduction
Thyroglossal duct cyst (TGDC) is a congenital problem due to the inability of thyroglossal duct to disappear during intrauterine development [1]. The thyroid gland develops from the median outgrowth of primitive pharynx at third week of gestation and it descends via the thyroglossal tract to the neck, passing in the front of the body of hyoid bone. It reaches its final position in the anterior neck inferior to the thyroid cartilage in the inferior pre-tracheal neck by the seventh week of gestation [2,3] . The thyroglossal tract usually disappears by the 10 th week of gestation [4]. However, approximately 7% of the general population have persistent duct and cystic degeneration of the duct form TGDC [3,5]. TGDC typically occurs before the age of 10 years but may occur in substantial minority of young adults [6,7] where they often appear after respiratory tract infection. It can occur along the route of migration of the thyroid gland from foramen cecum to the anterior neck [5]. It presents clinically as painless, slow progressive mobile midline anterior neck swelling, which moves vertically with swallowing or protrusion of tongue, due to their attachment to the hyoid bone [1]. TGDC can exist as cysts in the thyroid gland, laryngeal frame work, hyoid bone, lateral side of the neck and the tongue, thus presenting with respiratory and vocal symptoms [8]. Rarely, it may be secondarily infected, or associated with a fistula [1]. Thyroglossal duct cysts are mostly infra-hyoid in location, though it can be at hyoid or suprahyoid level [9]. Sistrunk's operation is the definitive treatment, this involves the excision of the TGDC with its tract extending to the foramen caecum along with the mid-portion of hyoid with which the tract is intimately related to ensure total excision of the remnants of thyroglossal duct [10]. This is to avoid incomplete excision that may result in recurrence [11]. This study presents the characteristics of thyroglossal duct cyst in children and the management outcome in our Centre.

Results
A total of 37 patients comprising 22(59.5%) males and 15(40.5%) females (M:F 1.4:1) were managed during this period. Their ages ranged from 13 days to 55 years (median 6 years). Majority of the patients were less than 10 years of age and from low socioeconomic status 26(70.2%). They all presented with a fluctuant midline progressive anterior neck swelling. One (2.7%) patient had an associated anterior neck ulcer whereas 3(8.1%) had discharging sinuses and they were all children ( Table 1). The duration of the symptoms prior to presentation varied from 1 week to 6 years (median: 6months). All the patients were referred by the family physicians; of which 3(8.1%) cases had incision and drainage of TGDC, but were referred due to recurrence of the cyst. Seven (18.9%) patients had TGDC infection prior to presentation in the hospital. Of these, infected sinus was observed in 2(5.4%) patients and infected cysts in 5(13.5%) patients. Four (10.8%) of these patients were managed successfully with antibiotics by the family physicians and 3(8.1%) were referred. They were, however managed with antibiotics for 5-11 days before surgical excision.

Discussion
The remnants of thyroglossal duct account for majority of anterior neck swellings in children unlike in adults [13], as observed in this study in which 70.3% were children. Although TGDC can be present at any age, it is often detected at the second decade of life [14] but majority of our patients were diagnosed in the first decade of life. This is similar to an earlier report in which the highest incidence was in the first decade of life [15]. TGDC have a bimodal age distribution with peaks at first and fifth decades of life suggesting that it is also common in the adult population [12,16,17] and the observed median age at presentation of 6 years is lower than the previously reported median ages of 17 and 31 years [16,18]. This may be due to the difference in age group of the cohorts of patients in each study, with children predominating the cohort of patients in this study. This median age at presentation suggests that majority of the patients presented late in the hospital after the onset of neck swelling. This may be due to initial presentation to the general practitioners who delayed in referring them to the specialists; it may also be due to the slow progression of the mass or the use of alternative medical therapy. The delayed referral of all the patients by the general practitioners and inappropriate surgery they offered the patients suggest that there is a need for continuous medical education for general practitioners to update their knowledge on the nature of the swelling and current surgical approach. The gender difference varies from one study to another and with age. We observed male preponderance in contrast Cytological evaluation with fine needle aspiration cytology (FNAC) can diagnose malignancy preoperatively, as the majority of thyroglossal duct cyst cancers are either papillary carcinoma of thyroid origin, or squamous carcinoma [1,16]. It is impossible to identify the thyroglossal duct cyst harboring mitotic lesion, but it should be suspected if the thyroglossal duct cyst is hard, irregular and rapidly growing with palpable cervical lymph nodes [26]. None of our patients had FNAC as part of preoperative assessment before surgery because there were no clinical and radiological evidences of malignancy. FNAC determines the patients with carcinoma prior to surgery and influences decision making in offering the best care to the patients. Thus, total thyroidectomy for comprehensive loco-regional control will be performed in addition to Sistrunk's operation which is the standard surgical approach for TGDC, with subsequent postoperative adjuvant therapy [3]. The postoperative histopathological reports of the excised specimens confirmed the preoperative diagnosis of TGDC, there was no malignancy or associated thyroid gland tissue within the cyst wall.
Earlier report shows correlation between preoperative and postoperative diagnosis [19], which demonstrated the appropriateness of clinical and radiological diagnosis preoperatively.
Histologically, TGDC are commonly lined by a combination of respiratory and squamous epithelium [16]. Though, high incidence of thyroid gland tissue within the TGDC wall and adjacent soft tissue has been reported [16].

What is known about this topic
• Thyroglossal duct is responsible for majority of anterior neck swellings in children; • It is often detected at the second decade of life, although TGDC can present at any age.

What this study adds
• The Sistrunk operation can be done in resource challenge environments without the use of surgical wound drain; • Patient can be discharged home on the same day of surgery, thus reducing the cost of hospital stay and without postoperative complications.

Competing interests
The authors declare no competing interests.

Authors' contributions
Author OSA conceived the study ideal, while authors OSA and OOO design the methodology. Authors OSA and OOO did literature search and also extracted relevant data from the hospital notes. The data analysis and the interpretation of the results were done by authors OSA and OOO. The manuscript was written by the authors OSA and OOO.

Acknowledgments
Thanks to Mr. Iwasokun of the medical record department who helped to retrieve the case notes that were used. Table   Table 1: socio-demographic data of the patients