Stage 0 colon/rectal carcinoma in situ; shows a cross-section of the colon/rectum. An inset shows the layers of the colon/rectum wall with abnormal cells in the mucosa layer. Also shown are the submucosa, muscle layers, serosa, a blood vessel, and lymph nodes.
Stage 0 (rectal carcinoma in situ). Abnormal cells are shown in the mucosa of the rectum wall.