Acute suppurative thyroiditis secondary to piriform sinus fistula: a case report.

We present a typical case of acute suppurative thyroiditis (AST), associated with a piriform sinus fistula. We illustrate the case with an ultrasound picture of a hypoechogenic perithyroid mass and a CT scan using intravenous iodine contrast showing a perithyroid hypodense mass with peripheral enhancement, the mass also having intrathyroid involvement. When clinical and radiological findings suggest the presence of AST, it is necessary to rule out the presence of a piriform sinus fistula by means of a radiological study with barium contrast. Piriform sinus fistula is a rare abnormality derived from the branchial arch which is directly related to recurrent episodes of AST; surgical excision is hence, necessary to avoid such episodes.