Goitre
Read about a goitre (sometimes spelt "goiter"), an abnormal swelling of the thyroid gland that causes a lump to form in the neck.
Read about diagnosing a goitre. If you think you have a goitre, see your GP. They can examine your neck to see if there's any evidence of thyroid gland swelling.
Read about treatment for a goitre, which can include medication, hormone therapy and surgery.