Thyroid Lymphoma

Abstract

This chapter discusses the investigation and diagnosis of thyroid lymphoma. The diagnosis of thyroid lymphoma is almost always made by the pathologist in patients thought clinically to have a primary thyroid carcinoma. Prior to surgery, staging investigations will usually have included a chest radiograph and a 131 I scan. The latter generally shows a cold nodule or a patchy or diffuse decrease in uptake. These appearances are indistinguishable from those of other thyroid neoplasms or chronic thyroiditis. Serological tests for antimicrosomal and antithyroglobulin autoantibodies are frequently positive in patients with thyroid lymphoma but do not help in establishing the diagnosis. Falling autoantibody level may herald the development of lymphoma in patients with known thyroiditis and should alert the clinician as to this possibility. A diagnosis of thyroid lymphoma may be made from fine needle aspiration cytology that is a safe procedure and provides rapid results. However, it does not provide a definitive pathological diagnosis that can only be achieved with a tissue rather than needle sample. The diagnosis of thyroid lymphoma is most easily established with a definitive surgical specimen and this is frequently the way in which it is made in practice. Histopathological rather than cytological examination enables the tumor subtype to be defined and determines subsequent treatment.