Primary echinococcal cyst of the thyroid: report of a case.

A case of primary hydatid disease of the thyroid, a rare location, is presented. The patient was a 50-year-old woman who presented with a neck mass at the thyroid region, which was noticed 2 months before her presentation. Although the clinical impression was of a neoplastic lesion (adenoma or carcinoma), a hydatid cyst was considered intraoperatively and confirmed by a frozen section histology. It was completely removed. No other sites of hydatid disease were found and the patient remained well postoperatively. In patients with a solitary cyst in the thyroid, the possibility of hydatid disease, though rare, should be always kept in mind, because a needle aspiration biopsy is a potentially harmful procedure.