Fig. 1

Imaging findings. A Ultrasonographic findings. A hypoechoic mass measuring 34 × 31 mm is observed in the lower pole of left thyroid lobe. B–D Computed tomography findings. A solid mass in the lower pole of left thyroid lobe (arrow) compresses the trachea and partially protrudes into the tracheal lumen, suggesting tracheal invasion. B Axial view, C coronal view, and D provides a 3D reconstructed view. E Bronchoscopic findings. A papillary structure approximately 3 cm in length (arrow) is visible within the tracheal lumen, indicative of tumor exposure