Evidence for colorectal sarcomatoid carcinoma arising from tubulovillous adenoma

Figure 3 Gross appearance of the surgically-removed rectosigmoid mass (A and B). A: The luminal side view demonstrates the proximity to the dentate line; anal skin is labeled for orientation; B: Upon sectioning the sample through the sagittal plane, the lateral view identifies the sarcomatoid smooth component (marked as S) underneath the velvety tubulovillous adenoma component (marked as TVA); C: Invasive adenocarcinoma with high nucleus/cytoplasm ratio within the deeper sections; D: Pancytokeratin was diffusely positive in both epithelial and mesenchymal components (× 20); E: Vimentin showed expression in the sarcomatous (S) component only, with no staining in the carcinoma (C) portion.