Mediastinal ectopic thyroid is quite rare, occurring in less than 1% of all ectopic thyroids. Frequent location of mediastinal ectopic thyroid in reported cases is anterosuperior mediastinum. CT findings of ectopic thyroid can be various and are dependent on several factors, such as its iodine content, the extent of tissue degeneration, and the presence of colloid cysts. This is a case of right paratracheal ectopic thyroid with nodular hyperplasia, mimicking metastatic nodal mass on both CT and 18 F-FDG PET CT in a patient with colon cancer.