Fig. 4

a Higher power view showing that solid papillary carcinoma with reverse polarity consists of numerous papillae closely packekd with cuboid to colomnar neoplastic cells. b Higher magnification focusing on one papillary structure. Tumor cells own cytoplasm which is located near the basal layer and near the fibrovascular cores, whereas the nucleus is located at the opposite side, giving the impression of reverse polarity (hematoxylin–eosin–saffron)