Anaplastic thyroid cancer, medullary thyroid cancer, primary thyroid lymphoma and primary thyroid sarcoma are rare thyroid cancers that comprise 5-10% of all thyroid malignancies. Unlike well-differentiated thyroid cancers, these malignancies have few treatment options and carry a worse prognosis. The literature surrounding these pathologies is limited, but remains an area of active research. Despite the rarity of these conditions, they remain an important part of the differential diagnosis for any thyroid nodule. Awareness of their presentation, work-up and management is critical for oncologists and head and neck surgeons. The purpose of this article is to provide a broad overview of these malignancies with an emphasis on emerging clinical research and therapies. (C) 2017 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.