Thyroid often carcinomas, although cancer can occur in any tissue that the thyroid consists of, including cancer of C-cells and lymphomas. Cancers from other sites also rarely lodge in the thyroid. Radiation of the head and neck presents a risk factor for thyroid cancer, and cancer is more common in women than men, occurring at a rate of about 2:1. In most cases, thyroid cancer presents as a painless mass in the neck. It is very unusual for thyroid cancers to present with other symptoms, although in some cases cancer may cause hyperthyroidism. Most malignant thyroid cancers are papillary, followed by
Computed tomography of the thyroid (PTCs) (Fig. 3). Incidentally detected cancers tend to be smaller in size and less likely to have distant metastasis, as compared to clinically suspected thyroid cancers. On CT scans, a malignant lesion is suspected when the margins are ill-defined and there is extra-thyroid extension, lymph node involvement, or invasion of the surrounding structures. The absence of these features does not exclude malignant tumours, especially papillary, follicular, and medullary thyroid carcinomas (Fig. 3). Therefore, ultrasound is the modality of choice for thyroid lesion evaluation, due to its superior spatial resolution compared to CT examinations. Sonographic features of malignancy are micro-calcifications, acoustic