Metastatic thyroid carcinoma to the parapharyngeal and retropharyngeal spaces: Systematic review with seven newly reported cases describing an uncommon presentation of a common disease

Abstract

Background: Metastatic thyroid carcinoma to retropharyngeal and parapharyngeal (RP/PP) lymph nodes is rare. Literature suggests previous lateral neck dissection (LND) may alter patterns of lymphatic drainage in the neck, predisposing to these less common sites of spread. Methods: PRISMA-guided systematic search for all published cases detailing RP/PP metastases of well-differentiated thyroid carcinoma from 1970 to 2019. Results: Seventy articles were identified and 44 were included, along with seven cases treated at our institution, totaling 239 cases. Cases represented both retropharyngeal (60.7%) and parapharyngeal (39.3%) metastases identified in the initial (27.6%) and recurrent (72.4%) setting. Conclusion: RP/PP metastases generally present in the recurrent setting. RP/PP metastases often represent high-risk disease, and surgical treatment is recommended.

Parapharyngeal Lymph Node Metastasis From Papillary Thyroid Carcinoma

“…Computed topography and MRI are the most frequently used imaging techniques to reach the diagnosis. 3,7 The minimal size for detection of LN metastases in this area by CT/ MRI is significantly smaller than the minimal size for clinical detection. 3 CT/MRI are also helpful in defining the extent of the tumor, its relationship with surrounding structures, its compartment of origin (prestyloid vs poststyloid), and might even suggest its histologic nature.…”

“…2 Studies have shown that .4% to 5% of patients with PTC can develop metastases in the retropharyngeal and the PPS. 3 These locations are associated with a younger age, a more aggressive disease, and a poorer prognosis. 3 A lymphatic vessel from the upper pole of the thyroid gland to the retropharyngeal lymphatic system has been described by Rouviere.…”

“…3 These locations are associated with a younger age, a more aggressive disease, and a poorer prognosis. 3 A lymphatic vessel from the upper pole of the thyroid gland to the retropharyngeal lymphatic system has been described by Rouviere. [1][2][3] It was reported in only 20% of the cases.…”

“…3 A lymphatic vessel from the upper pole of the thyroid gland to the retropharyngeal lymphatic system has been described by Rouviere. [1][2][3] It was reported in only 20% of the cases. [1][2][3] The tumor can then spread from the retropharyngeal lymphatic system to the PPS using an anatomical dehiscence behind the fascia of the superior constrictor muscle.…”

“…[1][2][3] The tumor can then spread from the retropharyngeal lymphatic system to the PPS using an anatomical dehiscence behind the fascia of the superior constrictor muscle. [1][2][3] For the recurrent cases, the metastatic parapharyngeal LN can be the result of a retrograde lymphatic drainage due to a compression by metastatic LN or the fibrosis resulting from a neck dissection, redirecting drainage to the LN of the PPS. 1,2,4 They might also be the consequence of hematogenous spread.…”