The small swelling or the lump in the throat area is generally referred to as Thyroid Goiter. Goiter is mainly of two types; one is the diffuse small goiter and the other is the nodular goiter. Whatever type of a thyroid goiter a person suffers from, the causes are almost same.
The major cause of Thyroid Goiter is the deficiency of iodine. Thyroid gland in the body needs plenty of iodine for manufacturing the thyroid hormones and when less iodine is supplied to the body, it results in expansion of the thyroid gland resulting in slumps in the throat area.
Another common cause of Thyroid Goiter is too much increase of thyroid stimulating hormone (TSH) as compared to a defect in the normal synthesis that takes places in the thyroid gland. When TSH is produced in large quantity, it comes out from the pituitary causing the thyroid to expand resulting in the enlargement in the throat area.