Metastatic spread of occult papillary carcinoma of the thyroid to the parapharyngeal space: a case report.

Metastasis from thyroid carcinomas to the parapharyngeal space is very rare. A forty-year-old male presented with progressive dysphagia and enlargement in the right upper neck. Examination showed medial displacement of the right palatine tonsil and the lateral oropharyngeal wall. A firm, submucosal mass measuring 4 x 3 cm was palpated. Computed tomography revealed a hypodense and heterogenic parapharyngeal mass with a calcified border. The mass was totally removed by a transcervical approach. Although frozen-section diagnosis was a benign lesion, histopathologic evaluation showed metastasis of papillary thyroid carcinoma to the parapharyngeal lymph nodes. Total thyroidectomy and bilateral selective neck dissection were performed, after which the tumor turned out to be papillary microcarcinoma (0.8 x 0.8 cm) in the right upper lobe of the thyroid gland. No locoregional recurrences or distant metastasis were observed during a three-year follow-up. The differential diagnosis of parapharyngeal masses should include metastatic thyroid carcinomas, for which a lymphatic route has been suggested between the thyroid gland and the parapharyngeal lymph nodes.