PRIMARY ADENOID CYSTIC CARCINOMA OF THE CERVICAL TRACHEA MIMICKING THYROID-TUMOR - CT EVALUATION

Objective: Our goal was to describe the CT characteristics of adenoid cystic carcinomas of the trachea mimicking thyroid tumors. Materials and Methods: Computed tomography of four patients with pathologically proved adenoid cystic carcinomas extending into the thyroid gland was retrospectively reviewed. One case was also examined with MR. Results: The masses encircling the trachea and circumferential thickening of the tracheal wall were demonstrated in all four cases. The longitudinal extent of the tracheal wall thickening was also demonstrated in all cases. The tumors had a broad base on the trachea and convex margin on the thyroid gland. They were all homogeneous, generally smoothly marginated, and isoattenuating on postcontrast CT scans. Conclusion: Adenoid cystic carcinomas were usually seen on CT scans as homogeneous masses encircling the posterolateral trachea with thickening of the tracheal wall in the transverse and longitudinal planes. These CT characteristics may be helpful in the differential diagnosis of adenoid cystic carcinomas mimicking thyroid tumors.