Ultrasonographic Characteristics of Pyriform Sinus Fistulas Involving the Thyroid Gland.

OBJECTIVES: Ultrasonography (US) has been considered to have a more limited role in the diagnosis of pyriform sinus fistulas than computed tomography. The aim of this study was to evaluate the US characteristics of pyriform sinus fistulas involving the thyroid gland in an attempt to improve our ability to diagnose this condition using US.

METHODS: Between 2005 and 2016, 14 patients with pyriform sinus fistulas presenting as suppurative thyroiditis or as thyroid nodules were enrolled in the study. Their US images were reviewed to identify US characteristics indicating the presence of an underlying pyriform sinus fistula and compared with the computed tomographic images.

RESULTS: A hypoechoic tubular lesion across the thyroid gland was identified in 9 patients (64.3%). Hyperechoic foci or echogenic lines were found within the lesion in 10 patients (71.4%). A hypoechoic rim was found at the boundary of the lesion in 7 patients (50.0%). A lesion emerging from the posterolateral aspect of the thyroid cartilage was found in 4 patients (28.6%). Thirteen (92.9%) of the 14 patients had 1 of these 4 findings.

CONCLUSIONS: Ultrasonography would be a useful diagnostic modality for indicating the presence of an underlying pyriform sinus fistula in patients with suppurative thyroiditis or a thyroid nodule and can be used as a first-line diagnostic tool to screen for pyriform sinus fistulas.