Cervical thymic cyst as a cause of acute suppurative thyroiditis.

A case of acute suppurative thyroiditis following a perithyroidal abscess, which was thought to have resulted from infection of a cervical thymic cyst, is reported herein. The patient was an 8 year old asthmatic Japanese boy who originally presented with tender swelling of the left anterior neck in July, 1986. Although pharyngography could not clearly demonstrate the pyriform sinus fistula, a hypoechoic area around the left lobe of the thyroid gland was noted on ultrasonography. Incisional drainage revealed Streptococcus milleri. A diagnosis of acute suppurative thyroiditis was established, and a cystic tubular mass was surgically resected from the left perithyroidal space some time later. Histopathological examination of the specimen revealed partly cystic thymic tissue along with parathyroid tissue. These observations suggested that acute suppurative thyroiditis in this case was caused by a perithyroidal abscess and that a perithyroidal abscess may also result from infection of a cervical thymic cyst.