The authors report a case of left parapharyngeal ectopic goitre, in which resection was followed by postoperative Horner's syndrome, and describe the difficult management of this entity.

A 25-year-old woman presented with upper oesophageal dysphagia and a well-demarcated left parapharyngeal mass displacing the great vessels laterally and posteriorly. The mass was resected via an exploratory neck incision. Histological examination of the operative specimen revealed hyperplastic thyroid parenchyma. The postoperative work-up revealed a eutopic and euthyroid thyroid gland. The postoperative course was marked by Horner's syndrome that persisted at 1-year follow-up.

Parapharyngeal ectopic thyroid coexisting with a functional thyroid is extremely rare. Parapharyngeal masses are usually derived from the parotid gland and nerves. Surgery of the parapharyngeal space can cause injury to the sympathetic trunk, responsible for Horner's syndrome, as in our patient.

Ectopic thyroid should be considered as a possible diagnosis of a parapharyngeal mass. Although rare, Horner's syndrome is a dreaded complication of surgery of the parapharyngeal space.