The most pre-cancerous condition for carcinoma colon is -

A polyp is a tumorous mass that protrudes into the lumen of the gut. GIT polyps may be of following types A. Non-neoplastic polyps (i)  Hyperplastic polyps Most common polyp of the large intestine Has no malignant potential. (ii) Hamartomatous polyps (a) Juvenile polyp → No malignant potential except in Juvenile polyposis syndrome (b) Retention polyp → No malignant potential except in Juvenile polyposis syndrome (c) Peutz Jeghers syndrome → Polyps are not premalignant but patients are at increased risk of developing extraintestinal carcinoma of pancreas, breast, lung, ovary and uterus. (B) Neoplastic polyps (i) Adenomatous polyp Tubular adenoma → Has malignant potential (villous more than tubular). Villous adenoma → Has malignant potential (villous more than tubular). (ii) Familial polyposis (FAP) syndrome FAP can be further classified into (a) Classic FAP syndrome Typically develop 500 to 2500 colonic adenoma. A minimum of 100 polyps (adenoma) is necessary for a diagnosis of classic FAP. (b) Attenuated FAP Fewer polyps (average, 30) Risk of cancer development is usually around 50%. (c) Gardner syndrome Polyps + multiple osteoma + epidermal cyst + Fibromatosis. (d) Turcot syndrome Polyps + CNS tumor (medulloblastoma, glioblastoma). (iii) Hereditary nonpolyposis colorectal cancer (HNPCC) syndrome Also, known as Lynch syndrome. Characterized by an increased risk of colorectal cancer and extraintestinal cancer particularly of the endometrium.