The clinical and pathologic spectrum of lymphoproliferative disorders affecting the thyroid is diverse. Primary lymphoma is an uncommon malignancy of the thyroid, comprising between 0.6 and 5 per cent of thyroid cancers. The majority of thyroid lymphomas are diffuse large cell of B-cell origin. In this case, a 43 year old woman has been diagnosed to have thyroidal lymphoma, marginal zone type, originating from the underlying Hashimoto's thyroiditis.