This clinical trial protocol describes implementation of a prospective observation protocol to standardize data collection and obtain permission to collect samples of PMC tumors in a cohort of PMC patients being followed with active surveillance. This will allow PMC tumors to be accurately classified as either stable or progressive over time and used for comprehensive molecular profiling if surgical removal is required during follow-up

Therefore, in order to ensure that we will have at least 459 patients with PTC being followed with active surveillance, we plan to enroll 500 total patients, of which 350 will have FNA diagnostic for PTC (of which 99% are expected to have PTC) and 150 patients will have FNA suspicious for PTC (of which 113 would be expected to have PTC). This sample size will enable us to estimate the 5 year disease progression rate requiring intervention to within ±4% at 95% confidence level (using binomial calculation under the assumption that the study is not stopped early and the progression rate is not higher than 10%).