Cricoid cartilage masquerading as a tumour on thyroid ultrasound

On ultrasound scanning of the thyroid gland in a sagittal plane, the cricoid cartilage can falsely create the impression of a mass in the gland if the transducer is angled slightly medially. The illusion of a mass is fortified on transverse view if the cricothyroid and inferior pharyngeal constrictor muscles, which lie between the upper pole of the thyroid gland and the cricoid cartilage, are misinterpreted as a solid lesion. The purpose of this study was to describe the ultrasound features of the cricoid cartilage and to determine the frequency in which a pseudolesion is created. In 15 of 26 volunteers the cartilage was seen as a hypoechoic structure surrounded by an anechoic halo and containing foci of calcification, closely resembling a thyroid nodule. In 11 of the subjects, with a mean age of 55 years, the cartilage was heavily calcified, poorly visualized and did not simulate a thyroid lesion. Awareness of the cause and appearance of this pseudolesion should help radiologists avoid a potential pitfall and prevent unnecessary invasive procedures.