Thyroglossal cysts and fistulae

Objective: This study aimed to observe the different diagnostic approaches and differential diagnosis of 20 cases of thyroglossal cysts and fistulas managed surgically. Methods: The medical records of patients treated for thyroglossal cysts in the department of Ear, Nose, Throat Surgery at regional hospital of CMH Dhaka, Comilla, Rangpur and Ibn Sina Medical College and Hospital Dhaka, from 2002 to 2009 were reviewed. History and examination reports were studied. Their medical records were reviewed for clinical presentations, investigations, operative findings, histopathology and treatment outcome. After a clinical diagnosis, they had individualized investigations (USG, MRI, radio iodine scan, FNAC etc) prior to the Sistrunk’s operation. This was a retrospective study. Results: In this study the site of presentation of thyroglossal duct cysts were 15% suprahyoid, 80% thyrohyoid and 5% supra sternal. Present study revealed that 95% swelling were in the midline. 50% of the study cases of swellings were 1-2 cm, 60% swellings were soft and cystic moved with swallowing, 30% were firm but mobile. Skin was free in 80% cases and 20% had sinuses. 60% cysts contained fibrous tissue and 30% cysts contained thyroid tissue. At an average follow up of 2 years, all are asymptomatic and well. Conclusion: Although the clinical and histological presentations of these 20 cases are not rare, they do illustrate how varied thyroglossal cyst can be with respect to patient age, anatomic site or associated sign and symptoms.


Introduction:
Thyroglossal cysts and fistulas constitute the most common anomaly in thyroid development and are generally considered to be distinct clinical entities.They are common congenital lesions presenting as midline soft cystic neck masses that move cranially on deglutition and protrusion of the tongue or as a midline fistula resulting from secondary infection and rupture of the cyst.
The thyroid anlage arises from the floor of the primitive pharynx between the tuberculam imper and the posterior third of the tongue during fourth week of intrauterine life.Originally hollow, it becomes solid as it migrates to the lower neck.The lower end divides into two portions that become the thyroid lobes.The sinus tract should atrophy at the 6 th week (5 th to 10 th weeks) but if it persists it becomes the thyroglossal duct in which a cyst can develop.The hyoid develops later on and joins from lateral end to medial resulting the tract running through the bone, sometimes penetrating the hyoid bone. 1,2Apart from this, the thyroglossal tract lies ventral to the body of hyoid bone and thyrohyoid membrane.There is no internal opening of the tract as the tongue and foramen caecum develops at a later date.Thyroid tissue may be present in the cyst wall up to 60% of cases.Lymphoid tissue which is responsible for repeated infections and variable amount of fibrous tissue depending upon degree of infection are also present in the cyst wall.The cyst contains thick viscous mucous.The epithelial lining is either pseudostratified ciliated columnar, simple columnar, flattened squamous epithelium.Various types of malignancies like adenocarcinoma, squamous cell carcinoma, and papillary carcinoma have been reported. 3 -6

Methods:
Patients of this retrospective study included twenty cases reported during 8 years period from January 2002 to December 2009 to the department of Ear, Nose, Throat Surgery, regional hospitals of Combined Military Hospital (CMH) Dhaka, CMH Comilla, CMH Rangpur and in Ibn Sina Medical College Hospital, Dhaka.The subjects of the study were of different age group, both male and female; all of them had a swelling in front of the neck.These study cases were diagnosed, investigated, treated and followed up for 2 years.The cases were diagnosed on the basis of clinical presentation; history regarding presence of other congenital abnormalities in the patient or in their family, physical examination of the neck, ear, nose and throat, general clinical investigations.Ultrasonography is an ideal initial technique for the differential diagnosis of a neck mass.Other tests like Radio isotope scanning of thyroid gland, thyroid hormone assay, MRI, FNAC were done prior to the Sistrunk's operation.Histopathological examinations were done after surgical excision in all the cases.The results have been analyzed.

Results:
The results have been furnished in tabulated form.The lowest and highest age limits found in this series were 3 years to 36 years respectively.

31-Above 1 05%
Total 20 100% Maximum numbers of patients were between the age of 01 to 10 years (table-I).

Sex
Number %

Male 12 60%
Female 08 40% Total 20 100% The patient comprising the study consisted of 12 male and 8 female patients.

Suprasternal 1 5%
Total 20 100% In this series according to the site of presentation 15% suprahyoid, 80% thyrohyoid, and 5% suprasternal cysts were found.No intralingual cyst was present.Treatment was done by surgical excision under general anesthesia.Sistrunk's procedure was followed in all the cases except one is which recurrence occurred due to incomplete removal of the cyst in spite of Sistrunk's operation.Recurrence occurred in 75% cases where Sistrunk's procedure was not followed and in one case recurrence occurred due to incomplete removal of the cyst (Table-VII).

Table-IV Consistency and mobility of cyst
In this series all the cases were treated by surgical excision under general anesthesia.Sistrunk's procedure was followed.Post operative period was uneventful.

Discussion:
Thyroglossal cyst is a congenital anomaly that arises from an epithelial remnant of the thyroglossal duct and is the common midline neck cyst.The most common clinical presentation of a thyroglossal cyst is a gradually enlarging painless mass at the anterior neck.No sex predilection has been reported and the mean age at presentation is 5 years (age range: 4 months to 70 years.Patient may also present in adult life. 6,8 n this serious most of the patients (75%) were of 5-20 years of age.One patient was 3 years of age; one patient was 36 years of age.25% of patient was above 4 years to 8 years of age group.Thyroglossal cyst becomes apparent in 2-4 years old child when baby fat subsides and irregularities of the neck are more readily apparent.Among the female, younger patients relatively reported earlier (between 5-16 years) probably due to their anxious parents.In this series male patient reported for treatment in any time of their life but only one female patient reported after the age of 16 which reflects our poor socioeconomic condition and reluctance of the female patient to be operated upon once they are married.The cyst may be 2.1% intralingual, 24.1% suprahyoid, 60.9% thyrohyoid, and 12.9% suprasternal. 8In this study, we found 15% suprahyoid, 80% thyrohyoid, and 5% suprasternal position of the cyst.
Although another case was suspected as suprasternal presentation later on found as a cold nodule of the thyroid isthmus which has been excluded from this study.Since opening is always secondary due to spontaneous or surgical drainage after infection. 9, 10Ninety five per cent cases present with a painless cystic lump that moves on swallowing or protruding the tongue (Tug sign).In our study all the patients presented with swelling in front of neck.75% patient did not complain of pain, 25% suffered from pain.Size suddenly increases of 25% of case.Intermittent mucoid discharge was present in 20% cases.If uninfected the cyst may be soft, fluctuant and mobile in all direction but more often it is so tense that is seen solid and many appear as fixed.This study reveals 60% soft, cystic mobile in all side, 30% firm but mobile and 10% tensed cysts with side to side restricted movement.When infected, the lump will be painful, the patient will have odynophagia and overlying skin will be red.
We consider ultrasonography to be the initial diagnostic modality of choice for a clinically suspected thyroglossal cyst 7 .CT-scan and MRI play only a supplementary role in more accurately delineating the anatomy of the lesion and are unnecessary routinely.Radioisotopic scanning ( 131 1) should be considered in all suprahyoid and intrahyoid lumps in addition to FNAC.In 65-75% of patients with a lingual thyroid, there is no other thyroid tissue.Serum thyroid hormones assay and TSH level should be estimated.In this series all this investigations were done.Study for Cytokeratin, Carcinoembryonic antigen may be done to differentiate squamous cell carcinoma. 4eatment should be done by excision including the body of the hyoid bone between the lesser horns to avoid damage to the hypoglossal nerve, after the tract has been dissected to this area, Some authors suggested that not only the body of the hyoid but a core of tissue between this and the foramen caecum should be removed.Sistrunk still has his name applied to the present day operation of choice, has adopted this suggestion. 11 -14The body of the hyoid between the lesser horns is divided.A segment of muscles were removed in continuity with the bony segments.The core was removed in a line drawn at 45 o to the body of the hyoid aiming at foramen caecum.
There is no need to open in to the oral cavity.
In this series Sistrunk's operation were done in all cases.
It is unwise to open an infected cyst.It should be aspirated with a wide bore needle to improve antibiotic penetration and allow resolution with a view to removal later on.In case of recurrence, if hyoid bone is not removed (85% recurrence) Sistrunk's procedure has to be carried out in case of sinus, the opening of the sinus is to be excised in an ellipse; a double Z-plasty often gives a better cosmetic result than simple closure.
In case of squamous cell carcinoma in a thyroglossal cyst, radical operation employing Sistrunk's procedure with bilateral neck dissection should be done after preoperative radiotherapy in case of papillary carcinoma (most common).A recent review from Slone Kettering suggests treatment should be with Sistrunk's operation and thyroid suppression with thyroxin. 15

Conclusion:
Thyroglossal cyst is a congenital condition commonly occurs in children usually in the midline of the neck, may also present in adult life.Diagnosis should be made in a midline swelling which moves on swallowing and moves upwards on protrusion of the tongue characteristically.The clinical and histological presentations are not rare; they do illustrate how varied thyroglossal cysts can be with respect to patient age, anatomic sites, or associated signs and symptoms.

Table - V
Presentation of thyroglossal cyst