All the following polyps are premalignant except: March 2011
Ans. C: Hyperplastic polyps It is now appreciated that hyperplastic polyps are without malignant potential Juvenile polyps that are single and have been completely excised carry no significant increased risk of malignancy. Multiple juvenile polyps can be a sign of the familial juvenile polyposis syndrome. This has a significant risk (approximately 10 per cent) of subsequent colon cancer and also a possible increased risk of cancers of the stomach and duodenum (first pa of the small intestine). Juvenile polyposis (JP) Autosomal dominant. Multiple hamaomatous polyps of the colorectum (98%), stomach (13%), small bowel (6%) Juvenile polyps are usually pedunculated, smooth, lobulated with a vulnerable surface. Diagnostic criteria: - 5 or more juvenile polyps in the colon or rectum; OR - One juvenile polyp and positive family history of JP; OR - Juvenile polyps outside the colon or rectum, i.e. stomach/small bowel. Family history positive in 20-50%, suggesting high incidence of spontaneous mutations or low penetrance. Children/ adolescents often presents with iron deficiency anemia, hypoproteinemia and retarded growth. Also rectal prolapse or other congenital abnormalities (15%) in CVS, Urogenital tract and CNS. Cancer risk: - Increased risk, lifetime risk of 20-60% for colorectal cancer. - Median age at diagnosis is 35-40 years. - Increased risk for gastric and duodenal cancers Genetic testing - Germline mutations of the SMAD4 and BMPR1A are detected in 11-25% and 18-30% of patients of JPC. - Gastric polyposis seems to be more frequent and severe in patients with SMAD4 mutations. Treatment - Colectomy and gastric surgery in severe polyposis. Familial adenomatous polyposis (FAP) Autosomal dominant inherited disease, > 100 colorectal adenomas, caused by germline mutations of the tumor suppressor gene APC (detectable in 80-90% of patients with typical FAP) Prevalence 1:10000 with penetrance close to 100%. 25% of patients with FAP do not have positive family history. These are de novo germline mutations. Polyp development stas in distal colorectum at an average age of 15 Majority of patients become symptomatic with bloody diarrhea by the age of 25 Extracolonic manifestation: - Up to 90% of patients with FAP develop polyps in upper GIT - 30-40% gastric fundic gland polyposis and 5-10% gastric adenomas - Risk for gastric cancer not increased. Major causes of death in colectomized FAP patients are duodenal and ampullary cancer. Spigelman classification for polyposis in upper GIT to allow adequate follow up. Extra-intestinal manifestation of FAP include: - Desmoid tumours (10-20%) - Epidermoid cysts (30-50%) - Fibromas - Osteomas (often in the mandibula) Congenital hyperophy of the retinal pigment epithelium (70%) - Dental abnormalities. Gardner's syndrome: - Polyposis, epidermoid cysts, osteoma Turcot's syndrome in FAP - Polyposis, CNS tumours (medulloblastoma) Increased risk observed for: - Hepatoblastoma, follicular thyroid cancer, brain tumours (usually medulloblastoma). Treatment: - Procedure: Proctocolectomy with ileal-pouch-anal anastomosis (IPAA): Gold standard. Peutz Jeghers syndrome (PJS) Autosomal dominant. Special type of hamaomatous GI polyp (PJ polyp) and mucocutaneous melanin pigmentations. PJ polyps occur throughout alimentary tract with predilection for the small bowel. Mostly jejunal. Esophagus is spared. Rarely nose, gallbladder and ureter. Polyps characterized by extensive smooth muscle aborization throughout polyp. Pigment lesions in 95% of patients but may disappear with age. Mostly lips, peri-oral and intra-oral mucosa. Diagnostic criteria: 2 or more PJ polyps - One PJ polyp and mucocutaneous pigment lesion - One PJ polyp and positive family history of PJS. Endoscopic or surgical excision of large or symptomatic polyps is recommended. Family history is negative in up to 45% of index cases indicating de novo germline mutations. Recurrent colicky abdominal pain due to intussusception in adolescence or young adulthood. Also occult bleeding with iron-deficiency anemia. Pigmentation not always present in childhood and may fade later in life. Intra-epithelial neoplasia predisposes to cancer - hamaoma-adenoma-carcinoma sequence Cancer risk: - 85% by age 70 years - 57% GI cancer. - Colorectal cancer most common with lifetime risk of 39%. Lifetime pancreatic cancer risk is 11%. Extraintestinal cancers include breast risk (31-50%), endometrium and ovary. Cancer uncommon before age 30 years. Almost all female patients with PJS develop potentially malignant ovarian tumour, the sex cord tumour with annular tubules (SCTAT). Malignant transformation in 20% of all cases. Seoli cell tumours considered as male equivalent of SCTAT with gynaecomastia. Genetic testing - PJS is caused by germline mutation of the STKII tumour suppressor gene.
Juvenile polyposis syndrome
Familial polyposis syndrome
Hyperplastic polyps
Peutz Jegher syndrome