PT - JOURNAL ARTICLE AU - Cristian Marco-Alacid AU - Mario López-Merseguer AU - Carlos Sánchez-Juan TI - Secondary thyroid malignancy from metastatic colon lymphoma AID - 10.1136/bcr-2018-228591 DP - 2019 Mar 01 TA - BMJ Case Reports PG - e228591 VI - 12 IP - 3 4099 - http://casereports.bmj.com/content/12/3/e228591.short 4100 - http://casereports.bmj.com/content/12/3/e228591.full SO - BMJ Case Reports2019 Mar 01; 12 AB - Primary thyroid malignancy is more frequent than secondary. This case report describes a colon lymphoma with unique thyroid metastasis. When a thyroid lesion appears in an extension study such as Positron emission tomography–computed tomography marked with 18F-2-fluoro-2-deoxy-D-glucose, it is recommended to perform an ultrasound. The correct study with ultrasound and cytology obtained through fine needle aspiration on thyroid lesion allowed to refine the diagnosis and provide the correct treatment.