Adenomatous polyps can be divided into three types, namely, tubular adenoma, villous adenoma and mixed adenoma.
Adenomatous polyp type (1) tubular adenoma: the most common, accounting for adenomatous the 80% interest. Occur in the rectum and sigmoid colon. Tubular adenoma spherical shape, smooth surface, may have congestion, punctate bleeding spots. Histological features of normal epithelial cells are densely arranged, dark stained high columnar epithelium replaced. Goblet cells decreased, cells arranged in glandular, tubular increase in the number. Tubular adenoma 1% -5%.
Adenomatous polyp type (2) villous adenomas: rare, more common in the rectum. Surface was lobulated, irregular. Histological features of villous epithelial processes were slender structure. This type of cancer is about 40% higher.
Adenomatous polyp type (3) Mixed adenoma: Most tubular adenomas to villous adenomas, Department of Development and the formation of mixed type, usually larger, much in the 2 cm in diameter. Both histological features of tubular adenoma and villous adenoma. Polyp surface is not smooth, showing papillary uplift. Cancer rate of 20%.