<prompt> 26 year old male presents to OPD with a discrete thyroid swelling. On neck USG , an isolated cystic swelling of gland is seen. How much percentage will be the risk of malignancy?4824123  <response>: - This is a case of an isolated cystic swellings. Risk of malignancy in this case is 24. - Risk of malignancies in thyroid swelling can be expressed as a factor of 12 known as rule of twelve - Isolated Thyroid swelling: Solid 24 Cystic 12 - Dominant Thyroid swelling: Solid 12 Cystic 6 - Generalized Thyroid swelling: 3 