BASICS
DESCRIPTION
- Cyst composed of epithelial remnants of the thyroglossal tract as it descends from foramen cecum at tongue base to the lower neck
- Midline neck mass at the level of the thyrohyoid membrane, closely associated with the hyoid bone, within 2 cm of the midline
- Often asymptomatic midline neck mass but can become infected and rapidly increase in size
- Majority are located between thyroid and hyoid, followed by suprahyoid, then suprasternal, and finally intralingual being the rarest location.
- System(s) affected: endocrine; metabolic; skin; exocrine
EPIDEMIOLOGY
Most common form of congenital midline cyst in the neck, yet rare to present clinically in neonatal period ‚
Incidence
- Majority of cases present in patients <30 years old.
- Predominant sex: male = female
Prevalence
Occurs in up to 7% of population ‚
ETIOLOGY AND PATHOPHYSIOLOGY
- Cystic expansion of a remnant of the thyroglossal duct tract
- Incomplete closure of the thyroglossal duct during gestation
- Persistence of the epithelial tract, the thyroglossal duct, during the descent of the thyroid from the foramen cecum to its final position in the anterior neck
- The thyroglossal duct tract usually atrophies and disappears by the 8th to 10th week of gestation.
- Portions of the tract and remnants of thyroid tissue associated with it may persist at any point between the tongue and the thyroid.
- Failure of the thyroglossal duct to atrophy and involute after descent of the thyroid in the 4th to 7th week of gestation
- Hypothesis: Lymphoid tissue associated with the tract hypertrophies at the time of a regional infection, thereby occluding the tract with resulting cyst formation
Genetics
- Usually sporadic; if familial, autosomal dominant is most common mode of inheritance.
- Familial occurrence is extremely rare.
COMMONLY ASSOCIATED CONDITIONS
- History of a recent upper respiratory tract infection
- Ectopic thyroid tissue found in almost half of cysts and rarely associated with ectopic thyroid gland
- Thyroid carcinoma (rare)
DIAGNOSIS
HISTORY
- Most often asymptomatic midline neck mass
- Can present as enlarged mass following URI or if infected then present with swelling, pain, dyspnea, dysphagia
- Foul taste in the mouth if the spontaneous drainage of cyst occurred by way of the foramen cecum
- Rare: severe respiratory distress from lesions at the base of the tongue, a lateral cystic neck mass, an anterior tongue fistula, or coexistence with branchial anomalies
PHYSICAL EXAM
- Neck mass, usually within 2 cm of the midline
- Rises in the neck with tongue protrusion and swallowing
- Nontender/slightly tender if not infected
- Infected thyroglossal duct cyst may manifest as tender mass with erythema, tenderness, fever, draining sinus, and may be associated with dysphagia, dysphonia, or stridor.
- Airway obstruction is possible with extension through the thyrohyoid membrane into preepiglottic space.
DIFFERENTIAL DIAGNOSIS
- Ectopic midline thyroid
- Dermoid cyst
- Thyroid adenoma of isthmus/pyramidal lobe
- Lymphadenitis/lymphadenopathy
- Cervical thymic cyst
- Sebaceous (epidermal) cysts
- Branchial cleft cyst
- Primary thyroid carcinoma
- Lymphatic malformations
- Lipoma
- Hypertrophic pyramidal lobes of the thyroid
- Laryngocele
- Hemangioma
- Teratoma
DIAGNOSTIC TESTS & INTERPRETATION
Initial Tests (lab, imaging)
- Assess thyroid function with TSH, T3, T4. Imaging (e.g., thyroid ultrasound) should also be ordered to identify a normal thyroid gland and to rule out ectopic thyroid tissue, which may represent the patient 's only functioning thyroid (1)[B].
- CT neck with contrast is helpful for preoperative evaluation, with optimal identification of cyst location and extent of spread as well as relationship to hyoid bone.
- MRI can also be useful, but in children, ultrasound provides minimal side effects and is effective in identifying the cyst (2)[B]. However, ultrasound has limitations, such as variability of appearance and similarity to other lesions (3)[B].
- Depending on location and possible airway involvement, fiberoptic or direct laryngoscopy can be performed (1)[B].
- Occasionally, if the cyst is infected, hemorrhagic, or has a high protein content, it may appear as hyperdense on CT scan, as an area of high signal intensity on T1- and T2-weighted MRI, and have an internal echo on US.
- Malignancy may be suspected if a soft tissue component exists within or around the cyst.
Follow-Up Tests & Special Considerations
- If a solid mass is encountered during excision of a suspected thyroglossal duct cyst, it should be sent for frozen section to rule out a median ectopic thyroid.
- Fine-needle aspiration (FNA) is the most reliable method for preoperative diagnosis of thyroid carcinoma, especially if done with US guidance.
Diagnostic Procedures/Other
Incision and drainage with resulting scarring may complicate resection. ‚
Test Interpretation
- Cyst lined with stratified squamous/pseudostratified ciliated columnar epithelium
- Thyroid tissue is seen in 25% of cysts.
- <1% of thyroglossal duct cysts have malignant tissue, usually well-differentiated thyroid carcinoma.
TREATMENT
GENERAL MEASURES
- Antibiotics for infections
- Pain control
MEDICATION
- Infected cysts/sinuses are first managed by treating the infection, allowing time for inflammation to decrease for elective surgery.
- The most common organisms are oropharyngeal flora including streptococcal species and anaerobes.
- Antibiotic coverage should include oral flora and take into account severity of infection.
First Line
- Oral antibiotic options
- Amoxicillin/clavulanate 500 mg/125 mg PO q8h; pediatric " ”amoxicillin 45 mg/kg/day divided BID
- Clindamycin 600 mg PO q8h; pediatric " ”30 mg/kg/day PO divided q8h
- IV antibiotic options
- Ampicillin/sulbactam 1.5 to 3.0 g IV q6h; pediatric " ”ampicillin 200 mg/kg/day IV divided q6h
- Clindamycin 600 mg IV q8h; pediatric " ”30 mg/kg/day IV divided q8h
Second Line
- For infections not responsive to above-mentioned IV antibiotics, incision and drainage could be required to culture organism and treat abscess.
- Coverage against methicillin-resistant Staphylococcus aureus is not recommended, unless identified by culture.
ISSUES FOR REFERRAL
After initial infection is treated with antibiotics, patient should follow up with otolaryngologist as outpatient in 2 weeks for discussion of surgical excision when acute inflammation has decreased. ‚
ADDITIONAL THERAPIES
Sclerotherapy: Percutaneous OK-432 injections are an alternative approach in patients who are not surgical candidates if the presence of malignancy can be excluded (4)[B]. ‚
SURGERY/OTHER PROCEDURES
- All thyroglossal duct cysts should be surgically removed.
- Incision and drainage should be avoided, but if necessary, incision should be placed so that it can be excised completely with an ellipse at the time of definitive resection.
- Without definitive surgical resection of cyst, there is a high risk of reinfection.
- Sistrunk procedure is the standard of care which involves removal of a portion of the hyoid bone (5)[A].
- Airway monitoring with continuous pulse oximetry for cysts that could cause airway compromise
- If airway compromise is imminent, then early intubation and airway protection is imperative.
- Inability to tolerate oral antibiotics especially in pediatric population may require admission.
- Poor response to IV antibiotics requiring incision and drainage of abscess
Discharge Criteria
No evidence of abscess, cyst responding to antibiotics, resolution of airway concerns, and follow-up established for eventual surgical resection. ‚
ONGOING CARE
FOLLOW-UP RECOMMENDATIONS
- Unrestricted if a thyroglossal duct is not removed, as many as half will become reinfected so surgical follow-up is critical.
- Infection before surgery is a well-described cause of recurrence.
Patient Monitoring
1 to 2 weeks after resection ‚
DIET
Unless have signs of dysphagia, then admission with IV fluids is appropriate. ‚
PATIENT EDUCATION
- High risk of recurrence if not surgically excised or if have multiple infections prior to excision
- Need for Sistrunk procedure rather than just incision and drainage
- High risk of recurrence if surgical removal attempted during infectious episode
- Even if incision and drainage is performed, patient will require formal surgical excision at a later date.
- Reassure family about likely absence of malignancy (if appropriate).
PROGNOSIS
- Recurrence after complete excision using Sistrunk procedure is reported to be as low as 2% but often <10% (5)[A]. In one study, Sistrunk procedure yielded a recurrence rate of 5.3%, compared 55.6% with simple excision (6)[A].
- Risk factors for recurrence
- Failure to excise the cyst completely
- Multiple prior infections
- Children <2 years of age, intraoperative cyst rupture, and presence of a cutaneous component
- Preoperative/concurrent infection of the cyst at the time of the surgery
- Most cases of thyroglossal duct cyst carcinoma are treated adequately by Sistrunk procedure, with a reported cure rate of 95%. Thyroidectomy and radioactive iodine therapy is only recommended for high-risk patients (1)[B].
COMPLICATIONS
- Most common complications include infection and recurrence.
- Infection occurs in up to half of cysts if not excised.
- Lingual location of thyroglossal duct cysts can cause respiratory distress.
- Malignant degeneration may occur (1 " “2%) if cyst is not excised; papillary carcinoma is most common.
- Must rule out primary thyroid carcinoma if thyroglossal duct cyst carcinoma is found
- Patient may require thyroid medication for life if ectopic midline thyroid is removed.
- Thyroglossal duct sinus or a thyroglossal duct fistula
REFERENCES
11 Oomen ‚ KP, Modi ‚ VK, Maddalozzo ‚ J. Thyroglossal duct cyst and ectopic thyroid: surgical management. Otolaryngol Clin North Am. 2015;48(1):15 " “27.22 Huoh ‚ KC, Durr ‚ ML, Meyer ‚ AK, et al. Comparison of imaging modalities in pediatric thyroglossal duct cysts. Laryngoscope. 2012;122(6):1405 " “1408.33 Sidell ‚ DR, Shapiro ‚ NL. Diagnostic accuracy of ultrasonography for midline neck masses in children. Otolaryngol Head Neck Surg. 2011;144(3):431 " “434.44 Ohta ‚ N, Fukase ‚ S, Watanabe ‚ T, et al. Treatment of thyroglossal duct cysts by OK-432. Laryngoscope. 2012;122(1):131 " “133.55 Galluzzi ‚ F, Pignataro ‚ L, Gaini ‚ RM, et al. Risk of recurrence in children operated for thyroglossal duct cysts: a systematic review. J Pediatr Surg. 2013;48(1):222 " “227.66 Rohof ‚ D, Honings ‚ J, Theunisse ‚ HJ, et al. Recurrences after thyroglossal duct cyst surgery: results in 207 consecutive cases and review of the literature. Head Neck. 2015;37(12):1699 " “1704.
ADDITIONAL READING
- Hirshoren ‚ N, Neuman ‚ T, Udassin ‚ R, et al. The imperative of the Sistrunk operation: review of 160 thyroglossal tract remnant operations. Otolaryngol Head Neck Surg. 2009;140(3):338 " “342.
- Ibrahim ‚ M, Hammoud ‚ K, Maheshwari ‚ M, et al. Congenital cystic lesions of the head and neck. Neuroimaging Clin N Am. 2011;21(3):621 " “639, viii.
- LaRiviere ‚ CA, Waldhausen ‚ JH. Congenital cervical cysts, sinuses, and fistulae in pediatric surgery. Surg Clin North Am. 2012;92(3):583 " “597, viii.
- Rosenberg ‚ TL, Brown ‚ JJ, Jefferson ‚ GD. Evaluating the adult patient with a neck mass. Med Clin North Am. 2010;94(5):1017 " “1029.
- Szybiak ‚ B, Golusin … „ski ‚ W. Operative and postoperative management of patients after neck surgery [in Polish]. Otolaryngol Pol. 2012;66(3):201 " “206.
CODES
ICD10
Q89.2 Congenital malformations of other endocrine glands ‚
ICD9
759.2 Anomalies of other endocrine glands ‚
SNOMED
Thyroglossal duct cyst ‚
CLINICAL PEARLS
- Often asymptomatic midline neck mass at the level of the thyrohyoid membrane, closely associated with the hyoid bone
- If patient has signs of dysphonia, dyspnea, or dysphagia, the airway must be evaluated.
- Ultrasound is a highly effective initial modality of evaluating pediatric thyroglossal duct cyst.
- Even after initial infection resolves, patient must be evaluated for Sistrunk procedure given high risk of recurrent infection.
- Malignant degeneration may occur (1 " “2%) if cyst is not excised; papillary carcinoma is most common.