Abnormalities of the third branchial arch are less common than those of the second arch and usually present with left thyroid lobe inflammation. This paper describes 15 cases of pyriform sinus fistulae of third branchial arch origin usually presenting as recurrent thyroid abscess on the left side.

A retrospective review of 15 cases of third arch fistulae managed 2000 and 2008, diagnosed based on histopathology and radiological evidence of a fistulous tract, and treated with fistulectomy with left hemithyroidectomy.

All patients (six boys and nine girls, aged three to 15 years) presented with recurrent low neck inflammation. Pre-operative ultrasound, computed tomography fistulography and barium swallow demonstrated a third arch fistulous tract, left-sided in all cases. The fistula was detected intra-operatively and pathologically in all cases. Surgery (successful in all cases) emphasised complete recurrent laryngeal nerve and ipsilateral pyriform sinus exposure, to facilitate tract excision, with left hemithyroidectomy. There was no recurrence over three to five years' follow up.

Paediatric recurrent low neck inflammatory episodes, due to thyroidal abscess, especially left-sided, should raise suspicion of pyriform sinus fistulae.