Fig. 1

Tubular adenoma with clear cell change. The striking tubule structures of the clear cells are accompanied by conventional tubular adenoma cells at low magnification with HE staining (a). The boundary between the clear cell and conventional components at high magnification with HE staining (b). The clear cell component is negative for PAS (c) and alcian blue staining (d). Both components are positive for CDX2 staining (e). The localization of CEA (f) expression is diffusely cytoplasmic for the clear cell component, and luminal cell apical for the conventional one. Ki67 labeling (g) is slightly lower in the clear cell component. d-g represent immunohistochemistry. Ultrastructural examination (h) of the boundary between the clear cell area (left) and the conventional adenoma (right) at low magnification is shown and multiple cytoplasmic lipid-like vacuoles surround the nuclei in the clear cells (i)