CD8A and Hashimoto thyroiditis: Tissue specimens from all study participants showed the presence of diffuse infiltrates of mononuclear cells localized between thyroid follicles; some of these cells stained positively for CD8 (Fig. 2a) or Bcl-2 (Fig. 2b), thus confirming the initial clinical diagnosis of Hashimoto's disease or lymphocytic thyroiditis [15, 16].