Piriform fossa sinus tract - a 15-year retrospective review with a focus on atypical neonatal presentations

Third and fourth branchial anomalies are rare, accounting for less than 10% of all branchial anomalies. The piriform fossa sinus tract (PFST) typically presents with left-side suppurative thyroiditis, although it can present earlier in neonates as a non-inflamed cystic neck mass. PFST poses a considerable diagnostic challenge with variable clinical and imaging features, leading to long delays to definitive diagnosis and appropriate management.

To analyse the patterns of presentation and imaging findings in children with PFST, with a particular focus on neonatal presentation.

This was a retrospective review of the clinical presentation, imaging findings and management in 16 cases of PFST presenting to our tertiary children's hospital between 2003 and 2018. Cases were identified by medical records and picture archiving and communication system (PACS) search using relevant International Classification of Diseases (ICD)-10 coding.

Age at presentation ranged from prenatal to 16 years, with a male-to-female ratio of 2:1. All patients presented with neck swelling. Thirteen patients (81%) had suppurative thyroiditis at initial presentation. Two patients had severe thyroiditis/mediastinitis that required intensive care unit admission. Three neonates presented with noninfected, asymptomatic large cystic neck masses; two of these were detected prenatally and misdiagnosed as lymphatic malformations with subsequent spontaneous clinical resolution that later represented with evidence of PFST. The PFST was on the left side in 15/16 (94%) patients. All patients had neck imaging before definitive diagnosis. Imaging studies included radiographs, ultrasound, computed tomography, magnetic resonance imaging and barium esophagram studies. No single modality was diagnostic of PFST in all patients. Seventy-five percent of patients had multimodal imaging before diagnosis. All PFSTs were confirmed by endoscopic visualisation. Management of PFST was by endoscopic cauterisation in 13 patients and open surgery in 2. One patient did not require surgical correction.

Our study highlights the complex nature of PFST. The anomaly is uncommon, has variable clinical and imaging features and may have a lengthy, complicated course if not considered at initial presentation. An episode of suppurative thyroiditis in a child should prompt investigation for PFST. We describe atypical presentations with cystic masses in neonates that appear to resolve but represent later as typical clinical features of PFST.