A thyroid nodule comprised numerous polyclonal plasma cells inside cellular fibroblastic stroma, with residual thyroid tissue in the centre of the nodule. There was no associated paraproteinaemia. The residual thyroid tissue suggests that the exuberant granulation tissue in this case represents an unusual reaction to a colloid nodule. As far as we know, this is the first adequately documented case of the so called plasma cell granuloma of the thyroid.