Coexistence of a Carotid Body Tumor and Thyroglossal Duct Carcinoma With Cervical Lymph Node Metastasis
A 78-year-old woman visited our clinic, presenting with a 3-year history of a midline neck mass in the region of the hyoid bone and bilateral cervical asymptomatic neck masses. There were no constitutional symptoms, including fever, night sweating, fatigue, dysphagia, dyspnea, and weight loss. She reported that the mass was progressively increasing in size. The rest of the history was unremarkable. Physical examination showed a 3×3-cm rubbery, non-tender, semi-fixed midline mass and several enlarged lymph nodes at level II and III bilaterally. There were no pulsations or bruits on auscultation of the lateral neck masses. The results of routine laboratory tests, including blood chemistry, complete blood cell count, coagulation study, serologic testing, and urine analysis, were unremarkable. Electrocardiogram and chest X-ray were within normal limits.\nComputed tomography (CT) with contrast showed an irregularly marginated, round, heterogeneously enhancing mass at the level of the hyoid bone and multiple enlarged lymph nodes bilaterally at level II to III (). Interestingly, the left-side neck mass was located at the carotid bifurcation, splaying the carotid bifurcation on a CT scan (). However, the CT scan did not indicate other instances of abnormal lymphadenopathy in the left neck. Furthermore, neck CT and sonography did not demonstrate any mass involving the thyroid (). Fine needle aspiration biopsy (FNAB) was done on the midline mass and right-side neck mass. The results of FNAB suggested the possibility of papillary carcinoma and lymph node metastasis from papillary carcinoma, respectively. From the above results, we made the tentative diagnosis of TGDC carcinoma with bilateral neck metastasis. We planned to resect the masses, including bilateral neck dissection, in accordance with TGDC with neck metastasis. Splaying of the carotid bifurcation, however, is usually indicative of a CBT. Through the head and neck tumor board, we decided that carotid arteriography should be preoperatively performed to differentiate a CBT from lymph node metastasis. The mass was confirmed as a highly vascular mass in the bifurcation of the carotid artery that was compressing the internal and external carotid arteries (). Ascending pharyngeal artery represented the major blood supply for this tumor. Our patient did not undergo carotid occlusion testing and embolization because of the potential complications. Results of screening for metanephrine and vanillymandelic acid in 24-hour urine samples were negative.\nSubsequently, the patient underwent wide excision of the midline neck mass, including resection of the hyoid bone, total thyroidectomy, central neck dissection and right-side selective neck dissection (levels II-V), involving resection of the sternocleidomastoid muscle, spinal accessory nerve, and internal jugular vein. Although there was mild adhesion between the midline mass and surrounding soft tissue, we obtained a generous resection margin (). During the exploration of left-side neck, we confirmed the CBT between external and internal carotid artery (). We did not try to remove the left-side neck mass (CBT) because it had a tendency to bleed when touched and the patient was elderly.\nHistological analysis revealed that a thyroglossal duct cyst was lined by a single row of columnar epithelium and the tumor was composed of small and large papillary structures with fibrovascular cores (). In addition, the tumor cells lining the papillary structures of the midline mass and cervical lymph nodes showed nuclear grooves and nuclear clearing, which are characteristic nuclear features of papillary carcinoma (). The final histopathologic diagnosis was consistent with TGDC papillary carcinoma with perithyroidal soft tissue extension and subsequent multiple lymph node metastasis (17 out of 55 lymph nodes). However, we could not demonstrate any evidence of papillary carcinoma in the thyroid gland.\nThe patient refused adjuvant therapy with 131I after surgery and was only treated with levothyroxine supplementation. At the 2-year follow-up, the patient remained free of disease.