title: Trans-oral robotic surgery and surgeon-performed trans-oral ultrasound for intraoperative location and excision of an isolated retropharyngeal lymph node metastasis of papillary thyroid carcinoma.
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.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, University of California, San Francisco. Electronic address: rgoepfert@ohns.ucsf.edu.
authors.forename: Ryan P
authors.initials: RP
authors.lastname: Goepfert
authors.affiliation: Division of Endocrinology, Department of Internal Medicine, University of California, San Francisco. Electronic address: chienying.liu@ucsf.edu.
authors.forename: Chienying
authors.initials: C
authors.lastname: Liu
authors.affiliation: Division of Head and Neck Oncologic/Endocrine Surgery, University of California, San Francisco. Electronic address: William.ryan@ucsf.edu.
authors.forename: William R
authors.initials: WR
authors.lastname: Ryan
mesh_terms: D002277:Carcinoma / Q000175:diagnosis / Q000556:secondary / Q000601:surgery*; D002291:Carcinoma, Papillary; D061765:Endoscopic Ultrasound-Guided Fine Needle Aspiration / Q000379:methods*; D005260:Female; D006801:Humans; D008197:Lymph Node Excision / Q000379:methods*; D008198:Lymph Nodes / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D008207:Lymphatic Metastasis; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods; D057605:Natural Orifice Endoscopic Surgery / Q000379:methods*; D019647:Oral Surgical Procedures / Q000379:methods*; D012371:Robotics / Q000379:methods*; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000175:diagnosis / Q000556:secondary / Q000601:surgery*; D013965:Thyroidectomy / Q000379:methods*