Primary Thyroid Lymphoma

Abstract

Eight cases of primary thyroid lymphoma were reported in a tertiary government hospital from January 2005 to August 2011. All patients presented with a diffuse enlargement of both thyroid lobes with associated obstructive symptoms. Five of these cases were extranodal marginal zone lymphoma and three were diffuse large B-cell lymphoma. Clinical features that would favor a thyroid lymphoma include tumor size of greater that 7cm, obstructive symptoms, clinical hypothyroidism or history of Hashimoto thyroiditis. Thus, these features must be considered in evaluating thyroid nodules during fine-needle aspiration biopsy. Histologically, extranodal marginal zone B-cell lymphoma shows vaguely nodular to diffuse infiltrates of small to intermediate size atypical lymphoid cells infiltrating the thyroid follicles, while diffuse large B-cell lymphoma shows sheets of large atypical lymphoid cells infiltrating the thyroid follicular epithelium. Keywords: Primary Thyroid Lymphoma, Extranodal Marginal Zone B-cell Lymphoma, Diffuse Large B-cell Lymphoma.