<prompt> Adenoma - carcinoma sequence is seen inFollicular thyroid carcinomaCarcinoma gall bladderCarcinoma stomachCarcinoma colon  <response>: Carcinoma colon 1177-LB 1179-B L 25thAdenocarcinoma of the colon: microscopically the neoplasm is a columnar cell carcinoma originating in the colonic epithelium. Macroscopically, the tumour may take one of four forms. Type 4 is the least malignant form It is likely that all carcinomas start as benign adenoma the so called adenoma-carcinoma sequence The annular variety tends to give rise to obstructive symptoms whereas the others more commonly willpresent with bleeding. Tumours are more common in the left colon and rectum. 