Very rare. The sinus piriformis corresponds to the pharyngolaryngeal recess: its internal wall forms the pharyngeal face of the aryepiglottic fold and its lateral wall is inside the posterior part of the thyroid cartilage. It is a fistula of the 4th endobranchial pocket. It is the persistence of the pharyngobranchial IV arch which runs from the bottom of the piriform sinus (close to the inferior thyroid cartilage horn) to the deep face of the homolateral thyroid lobe, just under the superior laryngeal nerve. There is initially no cutaneous fistula.

It may present as:

-        laterocervical swelling

-        febrile torticollis

-        basicervical pseudoadenopathy

-        laterobasicervical abscesses

-        pseudothyroiditis

Difficult diagnosis: CTscan, CTscan after barium meal, ENT endoscopy of the piriformis sinus fundus. Surgical resection which sometimes involves a partial thyroidectomy.

Anesthetic implications:

cervical surgery, risk of damage to the recurrent nerve

References:        

Updated: November 2017