Acute suppurative thyroiditis secondary to fistula of the pyriform sinus

: Acute suppurative thyroiditis is very rare and often related to congenital abnormalities of the branchial pouches or immunodeficiency. A case of acute thyroiditis due to fistula of the left pyriform sinus in a young man with no relevant history is reported. We review the embryology, diagnosis, and treatment of this rare entity.