A Rare Case Report of Thyroglossal Duct Cyst Carcinoma Coexisting with Thyroid Carcinoma in an Adolescent.

Background: Thyroglossal duct cysts (TDC) represent approximately 70% of all congenital neck masses, and up to 1% of them contain thyroid tissue malignancies. Clinical presentation of TDC carcinomas is usually indistinguishable from benign tumors preoperatively, and differential diagnosis can be challenging. We present a rare case of TDC carcinoma concurrent with thyroid cancer in an adolescent. Case Presentation. A 16-year-old Caucasian female, otherwise healthy, was referred with a painless, gradually expanding lump on the neck. Physical examination revealed a well-circumscribed, moderately hard, tender mass of the anterior neck midline anteroinferior to the hyoid bone. Imaging findings suggested TDC as the most likely diagnosis. The patient had a Sistrunk procedure under general anesthesia. Histopathological findings diagnosed a BRAFV600E-positive papillary thyroid carcinoma (PTC) in a TDC. A thyroid gland and neck ultrasound revealed a highly suspicious finding for malignancy right level VI lymph node, which was not confirmed by fine needle aspiration cytology (FNAC). Under general anesthesia, total thyroidectomy and central compartment lymph node neck dissection were performed. Histopathological findings revealed a thyroid parenchymal locus of PTC, as well as three lymph nodes infiltrated by PTC. The patient received adjuvant radioactive iodine ablation (RAI) therapy and is closely followed. Conclusion: TDC carcinomas in conjunction with thyroid carcinomas in young patients are rare. Preoperative diagnosis can be challenging, as the vast majority of neck masses in young patients are benign in nature, and most malignant tumors lack specific clinical features. The diagnostic accuracy of FNAC is considered unsatisfactory due to its frequently cystic nature. Definitive diagnosis is based on histopathological findings. Clinicians should maintain a high level of suspicion for coexisting thyroid malignancies. Although surgical extirpation of the malignancy is considered standard of care, the treatment of TDC cancer should always be individualized by a multidisciplinary team.

Clinical Controversy Surrounding the Differential Diagnosis of Branchiogenic Carcinoma.

Clinical evaluation, differential diagnosis, and management of a neck mass constitute commonly encountered problems for the head and neck surgeon. An asymptomatic neck mass in adults may be the only clinical sign of head and neck cancer. A 50-year-old female patient presented with a painless, slowly enlarging, left lateral neck lump. Ultrasonography described a possible lymph node with cystic degeneration, and fine needle aspiration biopsy only detected atypical cells of squamous epithelium. An open biopsy under general anesthesia was performed. Histopathological findings suggested the diagnosis of lymph node infiltration by squamous cell carcinoma of an unknown primary site, but differential diagnosis also included branchiogenic carcinoma arising in a branchial cleft cyst. A diagnostic algorithm for metastatic squamous cell carcinoma of an unknown primary site was followed, including positron emission tomography with computed tomography. The patient underwent panendoscopy and bilateral tonsillectomy, and an ipsilateral p16 positive tonsillar squamous cell carcinoma was detected. Further appropriate management followed. The existence of true branchiogenic carcinoma is controversial. When such a diagnosis is contemplated, every effort should be made to detect a possible primary site. Branchiogenic carcinoma, if exists at all, remains a diagnosis of exclusion.