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Tumours of the large intestine
• Benign:
• Polyp,is protrusion of the mucosa.
• Classification of intestinal polyps:
• Inflammatory. Inflammatory polyps ( pseudopolyposis in
ulcerative colitis)
• Meta plastic. Meta plastic or hyperplastic polyps
• Hammartomatous. Peutz- jet hers polyp
• Juvenile polyp
• Neoplastic. Adenoma.
• Tubular,tubulovillous,villus
• Adenocarcinoma,carcinoid tumour
•
Adenomatous polyp:
• Varies from tubular to villus.may be solitary and the cause of
rectal bleeding or sometimes villous and the cause of hypo
Kalaemia and Hypoalbuminaemia .the risk of malignancy increases
with their size
Familial adenomatous polyposis:
• defined to have more than 100 polyps and multiple extra
intestinal manifestation like endodermal( adenomas of
duodenum,stomach) or ectodermal like epidermoid cysts ,brain
tumours . And mesodermal like desmoid,dental problems,or
osteomas.
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Gardener's syndrome:
• familial polyps with epidermoid cyst and desmoid tumours.
Features of familial adenomatous polyposis:
• Autosomal dominant
• More than 100 colonic adenomas
• Prophylactic surgery
• Polyps and malignant tumours can develop in the duodenum and
small bowel.::
Treatment
• Colectomy with ileorectal anastamosis
• Restorative proctocolectomy with ileal pouch
• Total removal with end ileostomy.
Lynch syndrome:
• characterised by increased risk of colorectal cancer and also
cancer of endometrium,ovary,stomach and small intestine.
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Malignant:
• Epidemiology in UK colorectal cancer is the second most common
cause of cancer death .
• Aetiology: the accepted model arises from adenomatous polyps
after genetic mutation influenced by environmental factors . The
p53 gene mutated in carcinomas.
• Linkage between diet and colon cancer
• Ulcerative colitis
• Suggested after cholecystectomy increase risk
• Also increased risk after ureterosigmoidostom
• Pathology:
Macroscopic
• Four types; annular,tubular,ulcer,cauliflower.
Microscopic
• It is adenocarcinoma originating in the colonic epithelium