IgG4-positive extranodal marginal zone lymphoma arising in Hashimoto's thyroiditis: clinicopathological and cytogenetic features of a hitherto undescribed condition

摘要

Aims: Hashimoto's thyroiditis was recently divided into IgG4-plasma cell-rich and IgG4-plasma cell-poor subtypes. The former, also known as IgG4 thyroiditis, is associated with clinical, serological, sonographic and morphological features that are distinctive from those of the non-IgG4 subgroup. We describe an interesting case of IgG4-positive mucosa-associated lymphoid tissue (MALT) lymphoma arising in a background of IgG4 thyroiditis.