Thyroid nodules are collections of abnormal cells that form lumps in the thyroid gland. Between 90 and 95 percent of these nodules are noncancerous (benign). However, in uncommon cases, nodules are cancerous (malignant). For this reason, patients are urged to have nodules checked by a physician.

Thyroid nodules are the most common endocrine condition in the United States, according to the American Thyroid Association. Patients may have one nodule or several. In most cases, experts do not know why they form. However, risk factors include age and certain thyroid diseases.

In many cases, patients with thyroid nodules do not experience any symptoms and are unaware of their condition. However, some patients may discover a lump in the front of their neck that appears to grow larger over time. Large nodules may impair breathing or swallowing.

Thyroid nodules are often discovered by a physician during a routine physical examination or during an imaging test ordered for another condition. A fine-needle aspiration biopsy, which is an analysis of thyroid cells removed with a thin needle, can usually determine whether or not a nodule is cancerous.

Because the vast majority of nodules are benign, physicians usually prefer to monitor rather than have them surgically removed. In some cases, medications may be used to reduce the size of thyroid nodules or prevent the growth of new nodules. When cancer is present, experts generally recommend surgical removal of cancerous nodules and the thyroid gland.