Thyroid cancer is cancer of the thyroid gland. There are four forms: papillary, follicular, medullary and anaplastic. The most common forms (papillary and follicular) are fairly benign, and the medullary form also has a good prognosis; the anaplastic form is fast-growing and poorly responsive to therapy.Masses of the thyroid are diagnosed by fine needle aspiration (FNA) or frequently by thyroidectomy (surgical removal and subsequent pathological examination). As the thyroid concentrates iodine, radioactive iodine is a commonly used modality in thyroid carcinomas.Most often the first symptom of thyroid cancer is a nodule in the thyroid region of the neck, but only 4% of these nodules are malignant. Sometimes the first sign is an enlarged lymph node. Other symptoms that can be present are pain, changes in voice and symptoms of hypo- or hyperthyroidism
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