Thyroid lymphoma: recent advances in diagnosis and optimal management strategies

Primary thyroid lymphoma is rare, composing approximately 5% of all thyroid malignancies and less than 3% of all extranodal lymphomas. It typically presents as a rapidly enlarging goiter with associated compressive symptoms. Thyroid ultrasound and fine needle aspiration cytology, using flow cytometry and immunohistochemistry, remain the main modalities used to confirm the presence of lymphoma. The increasing use of an ultrasound-guided core biopsy to achieve an accurate diagnosis has further limited the role of surgery. An open surgical biopsy may still be required not only for definitive diagnosis but also to confirm the subtype of lymphoma. There are limited numbers of randomized or prospective trials to guide management, and controversy remains over optimal treatment. Treatment and prognosis of this disease can be dichotomized into two separate groups: pure mucosa-associated lymphoid tissue (MALT) lymphoma and diffuse large B-cell lymphoma (DLBCL) or mixed subtypes. Early stage (stage IE) intrathyroidal MALT lymphomas typically have an indolent course and may be treated with single-modality surgery, radiotherapy, or a combination of both. DLBCLs are more aggressive, and survival outcomes are highest with multimodal therapy incorporating monoclonal antibodies, chemotherapy, and radiotherapy. The prognosis is generally excellent but can be varied because of the heterogeneous nature of thyroid lymphomas. The aim of this paper is to discuss the changes in diagnostic modalities and to focus on the recent alterations in the management of this rare disease, including targeted therapies as well as the more limited role of the endocrine surgeon.