Thyroid Nodules

The term "thyroid nodule" refers to any abnormal growth that forms a lump in the thyroid gland.

The thyroid gland is located low in the front of the neck, below the Adam's apple. The gland is shaped like a butterfly and wraps around the windpipe or trachea. The two wings or lobes on either side of the windpipe are joined together by a bridge, called the isthmus, which crosses over the front of the windpipe.

A thyroid nodule can occur in any part of the gland. Some nodules can be felt quite easily, while others can be hidden deep in the thyroid tissue or located very low in the gland where they are difficult to feel.

These days, with modern imaging studies such as ultrasound (US), computerized tomography (CT), and magnetic resonance imaging (MRI), more and more thyroid nodules are being found incidentally. This means the nodules are found during studies that are being done for reasons other than examination of the thyroid gland. It is estimated that 4-8% of adult women and 1-2% of adult men have thyroid nodules that can be felt on physical examination, but closer to 30% of women have nodules detectable by ultrasound. In fact, the diagnosis of a thyroid nodule is the most common endocrine problem in the United States.

Although the majority of thyroid nodules are benign (not cancerous), about 10% of nodules do contain cancer . Therefore, the primary purpose for evaluating a thyroid nodule is to determine whether cancer is present.

Source: MedicineNet.com
http://www.medicinenet.com/thyroid_nodules/article.htm