Case #14: Neck Mass
Jeff Florek, M.D.

HPI: Patient is a 50-year-old Male who presents with chief complaint of neck swelling.  The Patient denies any other medical history but states the mass has been present for months. Patient states he feels that the mass is getting bigger in size and feels that it is affecting his swallowing.

Physical Exam/Workup: Physical exam reveals a soft, mobile midline mass on the anterior mid neck. Mass is non-tender. No overlying redness.

Bedside Ultrasound:

What are the features of this soft tissue mass that may help point toward a diagnosis?

Diagnosis
This neck mass is most consistent with thyroglossal duct cyst (TGDC).

Management
The patient will require outpatient workup and consultation with an ENT or general surgeon for surgical excision. However the patient may need additional imaging such as MRI. This is crucial to identify nearby structures as well as identify functioning thyroid tissue that may be contained within the TDGC that may result in hypothyroidism if removed.  In most cases an ultrasound should be sufficient and may be all that is needed for future surgical planning.

Ultrasound Education
When scanning soft tissue structures in the neck, use a linear probe. Scan perpendicular the skin and fan through the entirety of the mass in question, making sure to have enough depth to identify surrounding anatomy as well as color doppler flow to identify any vascular structures.

 TGDC’s originate form persistent epithelial remnants of the thyroglossal duct.  Thyroglossal duct cysts are a clinical diagnosis. Most are diagnosed in childhood but up to half can be diagnosed in the second decade of life or later.  TGDC’s are typically painless mobile, and most importantly are found in the anterior midline neck. These lesions may also move with protrusion of the tongue. TGDC are the most common congenital neck masses. These masses are most commonly located in the infrahyoid region however can be found any where in the midline neck area from the base of the tongue down to the suprasternal notch.  The classic ultrasound appearance would be a smooth, round, well-defined anechoic mass with thin walls and posterior enhancement. However they may also appear as homogenously hypoechoic masses  (as in this case) or pseudo-solid especially if there has been prior infection or inflammation of the cyst. In rare cases these masses may extend in to the larynx, in some cases displacing the epiglottis and causing respiratory symptoms such as sleep apnea or intermittent stridor. In general CT is rarely indicated. MRI is more useful in identifying the remnant tract that connects the cyst to the base of the tongue and further supports diagnosis of TGDC. This is not as easily visualized on CT.

In addition to thyroglossal duct cysts, the differential diagnosis for neck masses is broad. Dermoid cysts, which are usually heterogeneous, multi-loculated cysts with fatty components, are also found in the anterior midline of the neck.  Lipomas contain linear echogenic streaks that are parallel to the transducer. Branchial cleft cysts will have a similar appearance to thyroglossal duct cysts on ultrasound however will be found along the medial and anterior margin of the sternocleidomastoid muscle.  Lymph nodes have a characteristic ultrasonographic appearance.  With benign nodes having an echogenic central hilum with flow pattern on color Doppler imaging; whereas, malignant nodes have a disorganized peripheral pattern. Any punctate calcifications in lymph nodes should raise concern for malignancy, as well as any supraclavicular lymph node. Any masses that are warm, erythematous, or painful should be treated as infectious. History, ultrasound, and biopsy can further help delineate other infectious etiologies such as tuberculosis lymphadenitis and Cat-scratch disease (sub acute regional lymphadenitis), which may also present with tender inflamed lymph nodes in the neck.

Additional resources
1.        Valentino M, Quiligotti C, Villa A, Dellafiore C. Thyroglossal duct cysts: Two cases. J Ultrasound. 2012;15(3):183-185. doi:10.1016/j.jus.2012.04.003.
2.        Thabet H, Gaafar A, Nour Y. Thyroglossal duct cyst: Variable presentations. Egypt J Ear, Nose, Throat Allied Sci. 2011;12(1):13-20. doi:10.1016/j.ejenta.2011.03.001.
3.        Presentation I, Kutuya N, Kurosaki Y. Sonographic assessment of thyroglossal duct cysts in children. J Ultrasound Med. 2008;27(8):1211-1219. http://www.ncbi.nlm.nih.gov/pubmed/18645080.
4.        Ultrasound checks out suspicious neck lumps. 2007. http://www.diagnosticimaging.com/ultrasound/ultrasound-checks-out-suspicious-neck-lumps.