Table 3.

Thyroid lymphoma, pointers from the Workshop

Most common thyroid lymphoma is diffuse large B-cell lymphoma, less often MALT lymphoma, some follicular lymphomas, rarely other types (see below)

Designation of a disseminated thyroid lymphoma as ‘primary’ may be problematic but it is not of known clinical significance

Primary follicular lymphomas occur in the thyroid; however, they are currently probably under-recognized as some cases share many morphological, immunophenotypic and genotypic features with MALT lymphomas. Like the situation with some other types of extranodal FL, this distinguishes a subset of these cases from many nodal FL and suggests that they are a part of a separate and distinct entity; however, it also makes categorization of some individual cases controversial

Lymphoepithelial lesions occur in thyroiditis and varied types of thyroid lymphomas, i.e. they are NOT pathognomonic or even highly suggestive of a MALT lymphoma

Although controversial and in contrast to the situation in the salivary gland, documentation of a major clonal B-cell population in the thyroid strongly favours a B-cell lymphoma over an autoimmune disorder

The newly described FOXP1/IGH translocation is important in thyroid MALT lymphomas

MALT, Mucosa-associated lymphoid tissue; FL, follicular lymphoma.