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Thyroglossal Duct Cyst

BASICS

DESCRIPTION

- 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

  • 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 optionsAmoxicillin/clavulanate 500 mg/125 mg PO q8h; pediatric " ”amoxicillin 45 mg/kg/day divided BIDClindamycin 600 mg PO q8h; pediatric " ”30 mg/kg/day PO divided q8h
  • IV antibiotic optionsAmpicillin/sulbactam 1.5 to 3.0 g IV q6h; pediatric " ”ampicillin 200 mg/kg/day IV divided q6hClindamycin 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 recurrenceFailure to excise the cyst completelyMultiple prior infectionsChildren <2 years of age, intraoperative cyst rupture, and presence of a cutaneous componentPreoperative/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.