Patients who present with a rapidly expanding neck mass require rapid histopathologic confirmation of the diagnosis. If ATC is diagnosed, the patient's overall clinical status and TNM stage of the tumor should be determined. Treatment goals (aggressive versus supportive care) should be established by disclosing the status and risks/benefits, discussing the patient's values and preferences, and then having the patient make an informed decision. Patients with stage IVA/IVB resectable disease have the best long-term survival, particularly if a multimodal approach (surgery, IMRT for locoregional control, and systemic therapy) is used. Patients with unresectable stage IVB disease may also respond to aggressive multimodal therapy. Patients with distant metastases (stage IVC) only rarely have responded to traditional therapies, and if an aggressive approach is desired by the patient, a clinical trial should be considered. Hospice or palliative care is also an important component of managing patients with stage IVC disease. Readers interested in a complete list of our recommendations should consult the Supplementary Data.