Locally advanced asymptomatic papillary thyroid cancer presenting with retropharyngeal lymph node metastasis symptoms
Case Report

Locally advanced asymptomatic papillary thyroid cancer presenting with retropharyngeal lymph node metastasis symptoms

Roostam Kholmatov1, Obinwanne Emejulu1, Fadi Murad1, Rizwan Aslam2, Emad Kandil1

1Department of Surgery, 2Department of Otolaryngology, Tulane University School of Medicine, New Orleans, LA, USA

Correspondence to: Emad Kandil, MD, MBA, FACS, FACE. Division of Endocrine and Oncological Surgery, Department of Surgery, Tulane University School of Medicine, 1430 Tulane Ave, New Orleans, LA 70122, USA. Email: ekandil@tulane.edu.

Abstract: Papillary thyroid cancer (PTC) rarely metastasizes to the retropharyngeal lymph nodes. Managing patients with locally advanced primary PTC and metastasis located in distant anatomical areas is challenging. Herein, we report a 56-year-old patient with locally advanced asymptomatic PTC, who presented with obstructive airway symptoms due to the metastatic retropharyngeal lymph node. The patient underwent simultaneous total thyroidectomy, central lymph node dissection, en bloc resection of strap muscle and left laryngeal nerve via cervical approach and transoral resection of the metastatic retropharyngeal lymph node. Metastatic PTC should be included in the differential diagnosis of a retropharyngeal masses. Simultaneous total thyroidectomy of the primary thyroid cancer via a cervical approach and transoral resection of an isolated retropharyngeal metastasis is safe and feasible.

Keywords: Papillary thyroid cancer (PTC); retropharyngeal lymph node metastasis; clinical presentation; diagnosis; surgery


Submitted May 18, 2017. Accepted for publication May 25, 2017.

doi: 10.21037/gs.2017.06.03


Introduction

Papillary thyroid cancer (PTC) is the most common type of thyroid cancers. Patients with PTC are usually asymptomatic. However locally advanced thyroid carcinoma can manifest with dysphagia, dyspnea, and dysphonia because of involvement of esophagus, trachea and recurrent laryngeal nerve (1). It primarily metastasizes through the lymphatic system to the first echelon—central compartment (level VI) lymph nodes then to the lateral (levels II, III, IV, and V) neck compartments (2). PTC metastasis to the retropharyngeal space is rare with only a few reported cases (Table S1) (4,6-9).

The surgical approach for metastatic retropharyngeal lymph node can be challenging. There are several approaches for excision of retropharyngeal masses, including, transcervical, transmandibular and transoral.

In this article, we report a patient with locally advanced asymptomatic PTC, who presented with obstructive airway symptoms due to a metastatic retropharyngeal lymph node.


Case presentation

A 56-year-old female presented to the primary care provider with snoring, obstructive sleep apnea and dyspnea. On physical exam, a mass was noted on the posterior oropharyngeal wall. Computed tomography (CT) scan revealed an enhancing low density 2.1 cm × 1.3 cm mass, associated with asymmetrical soft tissue thickening in the left posterior pharynx just above the upper epiglottis (Figures 1-4). There was also a suspicious, low density 1.6 cm left thyroid nodule, with calcification (Figures 3,4). No other pathological lymphadenopathy, and no salivary glands pathology were reported.

Figure 1 Non-contrast enhanced CT scan (axial view) white arrow showing a bulging 2.1 cm retropharyngeal mass in the oropharynx.
Figure 2 Contrast enhanced CT scan (axial view) white arrow showing the retropharyngeal lymph node surrounded by low density area.
Figure 3 Contrast enhanced CT scan (sagittal view) white arrow showing the retropharyngeal mass and the enlarged left thyroid lobe with substernal extension (black arrow).
Figure 4 CT scan (frontal view) showing the left retropharyngeal mass (white arrow) and the left thyroid nodule with calcifications (black arrow).

After that the patient was referred to our clinic for evaluation of a posterior pharyngeal wall mass and an incidental left thyroid nodule. Physical examination revealed a bulging firm mass of the posterior oropharynx. Neck was supple, with palpable, mobile, non-tender 2 cm left thyroid nodule. Trachea was midline and no palpable cervical lymphadenopathy was noted. Flexible laryngoscopy showed a posterior pharyngeal wall mass at the hypopharynx-nasopharynx junction. Both vocal cords were mobile bilaterally.

Thyroid US revealed a left thyroid nodule 5.4×3.7×2.4 cm3 with calcification and minimal vascularity, the mass appeared to invade the strap muscle (Figures 5,6). No discrete nodules were noted in the right thyroid lobe. Ultrasound-guided fine needle aspiration (FNA) of the left thyroid nodule was positive for PTC.

Figure 5 Ultrasonographic image (sagittal view) showing a 5.44 cm heterogeneous nodule in the left thyroid lobe invading the strap muscle. SM, strap muscle; TN, thyroid nodule.
Figure 6 Ultrasonographic image (transverse view) showing 3.7 cm × 2.4 cm heterogeneous nodule in the left thyroid lobe invading strap muscle. SM, strap muscle; TN, thyroid nodule; SCM, sternocleidomastoid muscle.

We decided to perform simultaneous transoral excision of the retropharyngeal mass, and total thyroidectomy via the transcervical approach. First, the parapharyngeal mass was excised through a transoral 1.5 cm vertical incision over the mass and the cystic-appearing firm lymph node was dissected circumferentially safely. Then cervical incision was performed. We identified that the strap muscle was invaded by the left thyroid mass. The left recurrent laryngeal nerve was completely encased by the mass. We performed total thyroidectomy with en bloc resection of the strap muscles and en bloc resection of the left recurrent laryngeal nerve with central lymph node dissection (level IV).

Histopathology of the left thyroid lobe revealed a 2.5 cm × 2.0 cm papillary carcinoma, classic type, stage pT4aN1aM0, BRAFV600E mutant, and the left retropharyngeal lymph node was also positive for metastatic PTC. There was extrathyroidal extension present but the surgical margins were uninvolved by carcinoma. Nine of the twelve lymph nodes of the left central compartment were positive for metastatic PTC.

Postoperative period was uneventful except for hoarseness. Her voice was strong subjectively and objectively. The patient received radioactive iodine postoperatively and continued to show no evidence of recurrence after 2 years of follow-up.


Discussion

Papillary thyroid carcinoma is the most common and fortunately the least aggressive type of thyroid cancers. It usually grows slowly and has a favorable prognosis (14). However, PTC can be locally aggressive, and directly invading the nearby tissues. PTC most commonly metastasizes into the central compartment (level VI) lymph nodes, then the lateral (levels II, III, IV, and V) compartment nodes (2). Metastasis of PTC to the retropharyngeal lymph nodes (RPLN) is very rare and few cases are reported in the literature (Table S1).

Table S1
Table S1 A review of the literature of retropharyngeal and parapharyngeal metastasis from differentiated thyroid cancer
Full table

There are three possible scenarios to identify metastatic PTC to the retropharyngeal lymph nodes. In the first scenario, initially a RPLN mass is detected and there is no evidence of a primary thyroid neoplasm (6). After removing the RPLN and getting a histologic confirmation of metastatic PTC, an occult primary thyroid carcinoma is identified 1 to 6 months later (3,5,10,11,13). Probably this occurs due to a lymphatic pathway, described by Rouviere, connecting the posterior surface of the thyroid gland to the retropharyngeal lymphatic system (15). In the second scenario, recurrence of PTC can present with retropharyngeal lymph node metastasis (4,6-9). It is proposed that the lymphatic flow direction could become retrogradely after total thyroidectomy and neck dissection, leading to the RPLN metastasis (6). In the third scenario, both the primary thyroid tumor and the RPLN metastasis are diagnosed at the same time (3,6,9,12). Our case fits into the third scenario.

Recurrent cases of retropharyngeal PTC metastasis in most cases are clinically asymptomatic, whereas initial metastasis can manifest with various symptoms like swelling of the tonsils, snoring, fullness sensation in the throat, neck mass, or temporomandibular joint syndrome (3-13). In our case, the patient had both primary thyroid cancer and retropharyngeal metastasis. Despite the extensive local invasion, the primary thyroid cancer was asymptomatic and was found incidentally on CT scan as a benign thyroid nodule. Whereas the metastatic retropharyngeal lymph node manifested with obstructive symptoms: snoring, obstructive sleep apnea, and dyspnea. Our patient also had the BRAF mutation, which probably contributed to the aggressiveness of the cancer with the local invasion and the retropharyngeal lymph node metastasis.

Patients presented with recurrent disease in RPLN can be diagnosed with either CT or magnetic resonance imaging (MRI) (3-8,11-13). In our case, the physical exam and the flexible laryngoscopy were able to detect the retropharyngeal mass.

Transcervical ultrasound is not reliable in detecting retropharyngeal lymph nodes, although it is useful in revealing thyroid nodules and cervical lymphadenopathy. High serum thyroglobulin levels in recurrent cases of RPLN metastasis can also direct the clinician towards the diagnosis of metastatic PTC. FNA of the RPLN can be done either transcervically or transorally under CT or US guidance (3,4,6,7,12). However, FNA is not always accurate: non-diagnostic samples or even benign cytology has been reported with a proven metastatic disease (3). Our patient had both, a thyroid nodule and a RPLN, and we only biopsied the thyroid nodule because it was easily accessible. In cases of recurrent RPLN metastasis, FNA can be done transorally under US-guidance (4). In most cases of initial RPLN metastasis, histologic diagnosis is only established after resection of the mass. In our case, both the primary PTC and the retropharyngeal lymph node metastasis were diagnosed preoperatively.

PTC is a differentiated thyroid cancer with good prognosis. Excision of the primary tumor and neck dissection of the metastases provides a long-term disease-free and overall survival benefit (16-18). The ATA 2015 guidelines lack the nodal size threshold and the surgical management recommendations for retropharyngeal lymph node metastasis (18). This is because RPLN metastasis of PTC is very rare.

RPLN can be surgically excised via transcervical, transmandibular or transoral approaches (3-13). The transcervical approach provides a wide exposure of the retropharyngeal space, but the morbidity of such an extensive approach is rarely justified in the treatment of a metastatic differentiated thyroid cancer. This approach can cause injuries to the major vascular structures, lower cranial nerves, and the sympathetic chain. The transmandibular approach allows a significant exposure but can cause complications like pharyngocutaneous salivary fistula, poor healing of an osteotomy, damage to the teeth, and temporomandibular joint dysfunction.

The transoral approach is less invasive and allows adequate access for the excision of an isolated metastatic RPLN from an oncological point and avoids the potential morbidity of other approaches (7). Well-differentiated thyroid cancer LN metastasis doesn’t require excision with wide margins.

Goepfert et al. 2015 proposed transoral robot-assisted surgical excision of an isolated retropharyngeal thyroid metastasis. They report that robot-assisted approach offers a safe and effective dissection through the improved visualization and the dexterity in a small working space. Limitations of the transoral robotic approach are the cost, the availability of the machine, the need for extra training, and the loss of tactile feedback (4).

Our case is unique because the patient had both locally advanced primary tumor and an isolated RPLN metastasis. Because those lesions were in distant different anatomical regions, the retropharyngeal mass located high in the oropharynx and the primary thyroid tumor located in the lower neck with substernal extension, we performed simultaneous transoral and transcervical approaches for their excision. We believe that trying to access both lesions from single cervical approach would have done more harm than benefit in this case, by unnecessarily extending the surgical trauma by a very long incision, and risking injury to vital blood vessels and nerves.

The presence of BRAFV600E mutation is associated with a significantly higher risk of recurrence than BRAF wild-type tumors. Our patient had a BRAFV600E mutation and it probably contributed to the local aggressiveness of the primary tumor and the unusual retropharyngeal metastasis.


Conclusions

The possibility of metastasis from a papillary thyroid carcinoma in the differential diagnosis of lymph node swelling in the retropharyngeal space should be considered. Simultaneous transoral and transcervical approaches to the metastatic retropharyngeal lymph nodes and the primary differentiated thyroid tumors are feasible and safe.


Acknowledgements

We would like to thank Dr. Mary T. Killackey, MD, Chair, Department of Surgery, Tulane University School of Medicine.


Footnote

Conflicts of Interest: The authors have no conflicts of interest to declare.

Informed Consent: The authors were not able to reach the patient for the consent. However, none of the images used in the manuscript can be used to identify the patient.


References

  1. Wein RO. Management of the locally aggressive thyroid carcinoma. Am J Otolaryngol 2005;26:186-92. [Crossref] [PubMed]
  2. Wada N, Duh QY, Sugino K, et al. Lymph node metastasis from 259 papillary thyroid microcarcinomas: frequency, pattern of occurrence and recurrence, and optimal strategy for neck dissection. Ann Surg 2003;237:399-407. [Crossref] [PubMed]
  3. Lombardi D, Nicolai P, Antonelli AR, et al. Parapharyngeal lymph node metastasis: an unusual presentation of papillary thyroid carcinoma. Head Neck 2004;26:190-6. [Crossref] [PubMed]
  4. Shellenberger T, Fornage B, Ginsberg L, et al. Transoral resection of thyroid cancer metastasis to lateral retropharyngeal nodes. Head Neck 2007;29:258-66. [Crossref] [PubMed]
  5. Aygenc E, Kaymakci M, Karaca C, et al. Papillary thyroid carcinoma metastasis to the parapharyngeal space. Eur Arch Otorhinolaryngol 2002;259:322-4. [PubMed]
  6. Kainuma K, Kitoh R, Yoshimura H, et al. The first report of bilateral retropharyngeal lymph node metastasis from papillary thyroid carcinoma and review of the literature. Acta Otolaryngol 2011;131:1341-8. [Crossref] [PubMed]
  7. Goepfert RP, Liu C, Ryan WR. 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. Am J Otolaryngol 2015;36:710-4. [Crossref] [PubMed]
  8. Otsuki N, Nishikawa T, Iwae S, et al. Retropharyngeal node metastasis from papillary thyroid carcinoma. Head Neck 2007;29:508-11. [Crossref] [PubMed]
  9. Le TD, Cohen JI. Transoral approach to removal of the retropharyngeal lymph nodes in well-differentiated thyroid cancer. Laryngoscope 2007;117:1155-8. [Crossref] [PubMed]
  10. Sirotnak JJ, Loree TR, Penetrante R. Papillary carcinoma of the thyroid metastatic to the parapharyngeal space. Ear Nose Throat J 1997;76:342-4. [PubMed]
  11. Horvath M, Plas H, Termote JL, et al. Thyroid-related papillary carcinoma presenting as a cystic lesion in the parapharyngeal space. Rofo 1991;155:373-4. [Crossref] [PubMed]
  12. Ferrario F, Roselli R, Macchi A. Occult thyroid carcinoma presenting as a parapharyngeal mass. J Laryngol Otol 1995;109:1204-6. [Crossref] [PubMed]
  13. DiLeo MD, Baker KB, Deschler DG, et al. Metastatic Papillary Thyroid Carcinoma Presenting as a Retropharyngeal Mass. Am J Otolaryngol 1998;19:404-6. [Crossref] [PubMed]
  14. Fridman M, Savva N, Krasko O, et al. Initial presentation and late results of treatment of post-Chernobyl papillary thyroid carcinoma in children and adolescents of Belarus. J Clin Endocrinol Metab 2014;99:2932-41. [Crossref] [PubMed]
  15. Rouviere H, Tobias MJ. Anatomy of the human lymphatic system: a compendium translated from the original (French). Ann Arbor, Michigan: Edwards Bros. Inc., 1938:318.
  16. Beierwaltes WH, Nishiyama RH, Thompson NW, et al. Survival time and "cure" in papillary and follicular thyroid carcinoma with distant metastases: statistics following University of Michigan therapy. J Nucl Med 1982;23:561-8. [PubMed]
  17. Bernier MO, Leenhardt L, Hoang C, et al. Survival and therapeutic modalities in patients with bone metastases of differentiated thyroid carcinomas. J Clin Endocrinol Metab 2001;86:1568-73. [Crossref] [PubMed]
  18. Haugen BR, Alexander EK, Bible KC, et al. 2015 American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer: The American Thyroid Association Guidelines Task Force on Thyroid Nodules and Differentiated Thyroid Cancer. Thyroid 2016;26:1-133. [Crossref] [PubMed]
Cite this article as: Kholmatov R, Emejulu O, Murad F, Aslam R, Kandil E. Locally advanced asymptomatic papillary thyroid cancer presenting with retropharyngeal lymph node metastasis symptoms. Gland Surg 2017;6(6):733-737. doi: 10.21037/gs.2017.06.03