Pyriform sinus fistula as a cause of acute suppurative thyroiditis presenting as hyperthyroidism in a teenager with neurofibromatosis 1: a case report

A pyriform sinus fistula is a rare congenital anomaly that involves failure of obliteration of the third or fourth pharyngeal pouches during the embryological period. It is recognized as a cause of acute suppurative thyroiditis. We describe a case of a 14-year-old girl with Neurofibromatosis-1 that presented with malaise, sore throat, trouble sleeping, palpitations, dysphagia, and heat intolerance. Physical exam showed a tender thyroid nodule. Further evaluation revealed transient thyrotoxicosis. She had elevated free T4, low thyroid-stimulating hormone, and an elevated white blood cell count. A neck ultrasound and non-contrast computed tomography (CT) showed no evidence of a thyroid abscess. Radioactive iodine uptake revealed a cold nodule. Fine needle aspiration of the thyroid nodule diagnosed a thyroid abscess. Investigation of the anatomy during the direct laryngoscopy discovered a thyroid abscess caused by an infected pyriform sinus fistula. Antibiotics were given and the abscess was drained. After resolution of the infection, a hemi-thyroidectomy was performed to prevent re-infection. Acute thyrotoxicosis of unknown origin should prompt investigation for a thyroid infection and a primary cause such as a pyriform sinus fistula. If discovery of a pyriform sinus fistula is made, the fistula should be surgically removed after resolution of the infection in order to prevent recurrence of infection.