Abstract
Background
Retropharyngeal metastases are uncommon but a well-known location for regional spread of well-differentiated thyroid carcinoma (WDTC). Surgeon-performed, trans-oral ultrasound (SP-TO-US) and trans-oral robot-assisted surgical (TORS) excision represent a unique combination of technology and techniques in the treatment of isolated retropharyngeal thyroid metastases.
Patient findings
A patient with a history of T3N1b papillary thyroid carcinoma (PTC) previously treated with total thyroidectomy, left central and lateral neck dissection, and radioactive iodine presented with progressive elevations in serum thyroglobulin (Tg) from baseline of 0.2 to 0.6 μg/L. She was found to have an isolated 2.6 cm left retropharyngeal nodal metastasis on MRI that was confirmed to be PTC on fine needle aspiration biopsy. She underwent SP-TO-US for identification of the node in the operating room immediately prior to TORS excision. There were no complications. Additional radioactive iodine was administered. Post-treatment iodine scans revealed resolution of avid uptake in left retropharynx and return of Tg to 0.2 μg/L.
Summary
The combination of SP-TO-US and TORS represents a novel combination of technology and technique for treatment of isolated retropharyngeal metastasis in WDTC. Trans-oral ultrasound allows for rapid localization of the lesion in relation to the adjacent neurovascular structures in the parapharynx while the robot-assisted approach affords a safe and effective dissection through the improved visualization and dexterity in a small working space. Our patient had no complications and only short-term dysphagia that resolved after temporary diet alteration. Risks and long-term morbidities associated with classical approaches to the retropharynx including trans-cervical and trans-mandibular, particularly in a previously dissected field, are avoided through this trans-oral approach.
Conclusions
Retropharyngeal metastases are a known location for regional spread of WDTC and are amenable to evaluation and biopsy using TO-US by both surgical and non-surgical providers. In cases where lateral neck dissection has already been performed or when traditional transcervical or transmandibular approaches to the retropharynx represent a comparatively extensive procedure for isolated metastases, SP-TO-US and TORS are safe and effective combination for surgical management of disease.
1
Introduction
Retropharyngeal and parapharyngeal lymph nodes are uncommon but well-known locations for regional spread from of well-differentiated thyroid carcinoma (WDTC) . Surgical excision of isolated retropharyngeal lymph node metastases from WDTC has been well described via trans-cervical, trans-mandibular, and trans-oral approaches, including endoscopic-assisted trans-oral resection . Trans-oral robotic surgery (TORS) has been described for excision of metastatic retropharyngeal lymph nodes of oropharyngeal carcinoma and of parapharyngeal space tumors, but never for an isolated retropharyngeal metastasis from WDTC .
Trans-oral ultrasound has been used to localize retropharyngeal masses for fine needle aspiration (FNA) and prior to trans-oral resection in WDTC metastases . Given the demonstrated convenience and accuracy of intraoperative surgeon-performed ultrasound for tumor/lymph node localization in the central and lateral neck, we also report here on the use of intraoperative surgeon performed trans-oral ultrasound (SP-TO-US) for localization of a retropharyngeal node prior to TORS resection .
2
Patient
A 64-year-old woman with a history of pT3(s)N1b papillary thyroid carcinoma had had detectable serum thyroglobulin (Tg) of 0.2 μg/L increase to 0.6 μg/L (with undetectable anti-Tg) in the two years since she underwent a total thyroidectomy, left central and left lateral neck dissections by a different surgeon and radioactive iodine (RAI) treatment with I-131, 128 mCi. The post-treatment iodine scan showed only thyroid bed uptake. Repeated neck ultrasound evaluation was negative for persistent or recurrent nodal metastasis. A magnetic resonance imaging scan of the head and neck was obtained to further investigate for the source of thyroglobulin positivity, and it showed an isolated 2.6 cm left retropharyngeal lymph node ( Fig. 1 ). A positron emission tomography–computed tomography (PET–CT) of the body demonstrated the left retropharyngeal node as intensely hypermetabolic with a standardized uptake value (SUV) of 29 as well as a 10 mm left lower lung nodule that was mildly hypermetabolic, with an SUV of 1.4, and multiple additional non-specific lung nodules that measured less than 0.4 mm. She complained of mild ipsilateral, focal globus and mild dysphagia without alteration in diet. A CT-guided FNA of the retropharyngeal lymph node was positive for papillary thyroid carcinoma.
The patient underwent a TORS-assisted excision of the metastatic left retropharyngeal lymph node. After intubation and prior to the incision, we localized the enlarged lymph node with intraoperative SP-TO-US using an endocavitary transducer ( Fig. 2 ). The ultrasound visualized the node in its location lateral to the superior constrictor muscle and medial to the internal carotid artery and jugular vein and aided in placement of the mucosal incision and planning of the subsequent dissection ( Fig. 3 ). With the da Vinci® robot monopolar cautery, a vertical incision was made in the mucosal and superior constrictor muscle overlying by the node. The lymph node was visualized, dissected free from the surrounding tissue, and excised by the combination of da Vinci® robot arm and bedside-assistant instruments. The internal carotid artery was visualized and avoided. The sympathetic chain and glossopharyngeal nerve were not seen. There was minimal bleeding. A two-layer closure of the constrictor muscle and mucosa was made with simple-interrupted braided absorbable suture. Docking and console working times were 10 and 20 min, respectively. Suture closure of the incision line took 5 min.
There were no complications such as postoperative bleeding, hematoma, Horner’s syndrome, vocal paralysis, palate elevation paralysis, or lingual/hypoglossal nerve dysfunction. The patient stayed one night in the hospital. She was started on a liquid diet and advanced to a soft diet by discharge with no aspiration but some mild oropharyngeal pain and the need to concentrate for coordination of swallow. In the first month of follow up, her swallowing improved to near normal. She did experience a 10-lb weight loss attributed to prior mild pain (resolved by 1 month) and swallowing discoordination. At 2 months, her swallowing was normal with no further globus and no first-bite syndrome. At 2 months post-lymph node excision, she underwent a second course of RAI treatment with I-131, 125 mCi. The post-treatment iodine scan again showed thyroid bed uptake that was decreased compared to the prior scan, and no uptake in the left retropharyngeal region or in the lungs. At 4 months, her Tg was 0.2 μg/L. Her lung nodules, suspicious for metastatic disease, are currently being monitored with an increase at 6 months from 10 mm to 12 mm.
2
Patient
A 64-year-old woman with a history of pT3(s)N1b papillary thyroid carcinoma had had detectable serum thyroglobulin (Tg) of 0.2 μg/L increase to 0.6 μg/L (with undetectable anti-Tg) in the two years since she underwent a total thyroidectomy, left central and left lateral neck dissections by a different surgeon and radioactive iodine (RAI) treatment with I-131, 128 mCi. The post-treatment iodine scan showed only thyroid bed uptake. Repeated neck ultrasound evaluation was negative for persistent or recurrent nodal metastasis. A magnetic resonance imaging scan of the head and neck was obtained to further investigate for the source of thyroglobulin positivity, and it showed an isolated 2.6 cm left retropharyngeal lymph node ( Fig. 1 ). A positron emission tomography–computed tomography (PET–CT) of the body demonstrated the left retropharyngeal node as intensely hypermetabolic with a standardized uptake value (SUV) of 29 as well as a 10 mm left lower lung nodule that was mildly hypermetabolic, with an SUV of 1.4, and multiple additional non-specific lung nodules that measured less than 0.4 mm. She complained of mild ipsilateral, focal globus and mild dysphagia without alteration in diet. A CT-guided FNA of the retropharyngeal lymph node was positive for papillary thyroid carcinoma.
