Great cervical venous tumoral thrombosis of melanotic medullary carcinoma thyroid: Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography enabled diagnosis and radiotherapy planning.

The authors report an extremely rare occurrence of a massive tumor thrombus involving right internal and external jugular veins extending into superior vena cava from a still rarer melanotic medullary carcinoma thyroid in the postoperative follow-up. The case was managed by hypofractionated intensity modulated radiotherapy technique with gratifying results.