True about neoplastic colorectal polyps -a) Sessile polyps > 1 cm is malignantb) MC site is colon and rectumc) Adenomatous polyp is premalignantd) Tubular adenoma is malignante) Pseudpolyps are premalignant
**Core Concept**
Colorectal polyps are neoplastic growths that can be benign or malignant, and understanding their characteristics is crucial for early detection and treatment of colorectal cancer. The neoplastic potential of colorectal polyps is determined by their histological type, size, and degree of dysplasia.
**Why the Correct Answer is Right**
The correct answer highlights the premalignant nature of adenomatous polyps. Adenomatous polyps, also known as adenomas, are characterized by the presence of dysplastic epithelial cells and the potential to progress to colorectal cancer. This process is thought to occur through the accumulation of genetic mutations in the adenoma-carcinoma sequence. The larger the adenoma, the higher the risk of it containing high-grade dysplasia or invasive cancer. Adenomatous polyps are classified into three types: tubular, villous, and tubulovillous, with villous adenomas having the highest malignant potential.
**Why Each Wrong Option is Incorrect**
**Option A:** Sessile polyps > 1 cm is malignant - While large sessile polyps do have an increased risk of containing high-grade dysplasia or invasive cancer, the size criterion is not a reliable indicator of malignancy. The risk of malignancy is also influenced by the histological type and degree of dysplasia.
**Option B:** MC site is colon and rectum - While the colon and rectum are the most common sites for colorectal polyps, the rectum is actually the most common site for colorectal cancer. However, this option is not directly related to the premalignant nature of neoplastic colorectal polyps.
**Option D:** Tubular adenoma is malignant - Tubular adenomas are a type of adenomatous polyp, but they have a lower malignant potential compared to villous adenomas. While there is still a risk of malignancy, it is not as high as in villous adenomas.
**Option E:** Pseudopolyps are premalignant - Pseudopolyps are actually a type of inflammatory polyp that can occur in conditions such as ulcerative colitis. They are not premalignant and do not have the same neoplastic potential as adenomatous polyps.
**Clinical Pearl / High-Yield Fact**
The adenoma-carcinoma sequence is a key concept in understanding the pathogenesis of colorectal cancer. Adenomatous polyps can be removed during colonoscopy, and regular surveillance is recommended to detect any new or persistent polyps. Early detection and removal of adenomatous polyps can prevent the development of colorectal cancer.
**Correct Answer: C. Adenomatous polyp is premalignant**