Follicular adenoma thyroid nodules are more common than most people realize. You have a 1 in 10 chance of developing a thyroid nodule, and 9 out of 10 nodules are adenomas (benign). Some sources report that as many as 50% of people have them. The majority of these are undiagnosed and do not cause problems. The specific incidence of follicular adenoma thyroid nodules (as differentiated from other types of non-cancerous thyroid nodules) is not indicated.