Quiz Answer: D. Management of this finding involves excision via the Sistrunk procedure

Explanation: A midline neck mass is most likely to be a thyroglossal duct cyst (TGDC). This may occur when the thyroglossal duct–an embryonic structure that allows for the descent of the thyroid gland from the ventral pharynx to the midline of the neck–fails to involute completely.

[A] Of the thyroglossal duct cyst associated malignancies, papillary thyroid carcinoma (PTC) histologically makes up the vast majority of cases. Follicular carcinoma, squamous cell carcinoma, and other types of thyroid epithelial neoplasms have been described, but they are in contrast very uncommon. [B] A TGDC is generally mobile with swallowing, however it can sometimes be fixed when there is an associated malignancy.

Management of TGDC most often involves excision via the Sistrunk procedure. This procedure entails removal of the cyst, along with the central portion of the hyoid bone and a core of tissue between the hyoid bone and the foramen cecum. Even in malignancies associated with TGDC, this procedure is preferred and has been shown to be a significant predictor of overall survival. Some patients with a malignancy have benefitted from thyroidectomy as well. [C] Thyroglossal duct cyst associated malignancies are difficult to diagnose on FNA alone–FNA has a reported true positive rate of 53% and a false negative rate of 47%. Diagnosis is also difficult to establish on imaging studies. Instead, a diagnosis of a primary TGDC malignancy requires the histologic demonstration of an associated thyroglossal duct remnant that is lined by respiratory epithelium, squamous epithelium, or a combination of both.

References: Thompson LDR, Herrera HB, Lau SK. Thyroglossal Duct Cyst Carcinomas: A Clinicopathologic Series of 22 Cases with Staging Recommendations. Head Neck Pathol. 2017;11(2):175-185. doi:10.1007/s12105-016-0757-y

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5429280/

Quiz Answer: C

Explanation: This patient’s HPV+ tonsillar squamous cell carcinoma will most likely spread first to the upper anterior cervical (i.e. jugular) lymph nodes. Initial spread via lymphatics is true of most carcinomas—head and neck squamous cell carcinoma included—whereby tumor cells spread from the primary site to regional lymph nodes. Jugular lymph nodes are found in Levels II-IVa, with Level II (upper jugular) being the most commonly involved nodal level. Level II lymph nodes of the neck most often contain metastatic deposits from malignancies of the nasal and oral cavities, nasopharynx, oropharynx, hypopharynx, larynx, and major salivary glands. Assessment of regional lymph node status is crucial for tumor staging and further imaging studies should be planned accordingly.

References:

Köhler HF, Franzi SA, Soares FA, Torloni H, Kowalski LP. Distribution of Metastatic Nodes in N0-1 Patients with Tonsillar Squamous Cell Carcinoma and Its Implications for Selective Neck Dissection. Turk Arch Otorhinolaryngol. 2018 Sep;56(3):139-144. doi: 10.5152/tao.2018.3420. Epub 2018 Sep 1. PMID: 30319869; PMCID: PMC6177493. https://pubmed.ncbi.nlm.nih.gov/30319869/

Candela FC, Kothari K, Shah JP. Patterns of cervical node metastases from squamous carcinoma of the oropharynx and hypopharynx. Head Neck. 1990 May-Jun;12(3):197-203. doi: 10.1002/hed.2880120302. PMID: 2358329. https://pubmed.ncbi.nlm.nih.gov/2358329/