Large Bowel Pathology PDF

Lab 6 Pathology of large intestine Objectives 1- know types of inflammatory bowel disease. 2- Describe the morphological pathological changes of inflammatory bowel disease (gross and microscopical) 3- Describe the morphological pathological changes of adenoma and colorectal carcinoma (gross and mic...

Lab 6 Pathology of large intestine Objectives 1- know types of inflammatory bowel disease. 2- Describe the morphological pathological changes of inflammatory bowel disease (gross and microscopical) 3- Describe the morphological pathological changes of adenoma and colorectal carcinoma (gross and microscopical) Crohn's disease. Segmental distribution of the lesions (skip lesions) The middle portion of terminal ileum has a thickened wall and the mucosa has lost the regular folds. The serosal surface demonstrates reddish indurated adipose tissue that creeps over the surface(creeping fat). Other gross features are ulcer and fissure Crohn's disease is characterized by transmural inflammation. inflammatory cells (the bluish infiltrates) extend from mucosa through submucosa and muscularis and appear as nodular infiltrates on the serosal surface with pale granulomatous centers.  Colon_Crohns1.jpg Microscopic Features of Crohn Disease: There is considerable overlap in histologic features between Crohn disease and ulcerative colitis. Deep ulcers and fissures, transmural inflammation, and epithelioid granulomas are diagnostic hallmarks of Crohn disease In this picture, a small focus of uninvolved mucosa in the center is surrounded by ulcers on either side. There is transmural inflammation and numerous lymphoid aggregates and granulomas. Medium power view of a knife-like fissure extending from the mucosa into the superficial aspect of the muscularis propria. Non-caseating epithelioid granulomas are one of the diagnostic hallmarks of Crohn disease. This image shows a large epithelioid granuloma within muscularis propria formed by epithelioid cells, giant cells and lymphocytes. High power view of the granuloma of the Crohn's disease which is demonstrated here with epithelioid cells, giant cells, and many lymphocytes ulcerative colitis. Inflammation tends to be continuous along the mucosal surface and tends to begin in the rectum. The mucosa becomes eroded,, which shows only remaining islands of mucosa called "pseudopolyps". Pseudopolyps. The remaining mucosa has been ulcerated away and is hyperemic. Low power view of a section from a colectomy specimen. The inflammation is superficial and limited to the mucosa and upper part of submucosa, without evidence of transmural inflammation. Microscopically, the inflammation of ulcerative colitis is confined primarily to the mucosa and upper part of submucosa., the mucosa is eroded by an ulcer that undermines surrounding mucosa The colonic mucosa of active ulcerative colitis shows "crypt abscesses" in which a neutrophilic exudate is found in glandular lumens. The submucosa shows intense inflammation. The glands demonstrate loss of goblet cells and hyperchromatic nuclei with inflammatory atypia. Crypt abscesses are a histologic finding more typical with ulcerative colitis. Tumor of colon Various gross appearances of adenomatous polyps. A, Sessile polyp. B , Pedunculated polyps. Tubular adenoma. Small adenomatous polyp in the middle of the colon seen on left side. It has smooth surfaces and sessile. On the right side larger ones tend to be coarsely lobulated and have slender stalks with hemorrhagic surface. Small ones are virtually always benign. Those larger than 2 cm carry a much greater risk for development of a carcinoma. Ttubular adenoma have more crowded, disorganized glands than the normal underlying colonic mucosa. Goblet cells are less numerous and the cells lining the glands of the polyp have hyperchromatic nuclei. Villous adenoma is shown above the surface at the left, and in cross section at the right. They generally are sessile, up to 10 cm in diameter, velvety or cauliflower-like masses projecting 1 to 3 cm above the surrounding normal mucosa and larger than a tubular adenoma. A, Sessile adenoma with villous architecture, their histology is that of frondlike villiform extensions of the mucosa , covered by dysplastic, sometimes very disorderly columnar epithelium. B, Portion of a villous frond with dysplastic columnar epithelium on the left and normal colonic columnar epithelium on the right. Familial adenomatous polyposis, the inheritance pattern is autosomal dominant. Adenocarcinoma of the colon Carcinoma of the cecum.Tumors in the proximal colon tend to grow as polypoid, exophytic masses that extend along one wall of the capacious cecum and ascending colon. Obstruction is uncommon These are referred to as "apple core lesion" or "napkin-ring" lesion. Carcinomas in the distal colon tend to be annular, encircling lesions that produce so-called napkin-ring constrictions of the bowel. The margins of the napkin ring are classically heaped up, beaded, and firm, and the midregion is ulcerated. The lumen is markedly narrowed, and the proximal bowel may be distended. Adenocarcinoma arising in a villous adenoma. The surface of the neoplasm is polypoid and reddish pink. This neoplasm was located in the sigmoid colon. Adenocarcinoma of colon. The neoplastic glands are long and frond-like, similar to those seen in a villous adenoma. The growth is primarily exophytic (outward into the lumen) Adenocarcinoma of colon , the neoplastic glands have crowded nuclei with hyperchromatism and pleomorphism,no normal goblet cells are seen. lumen containing bluish mucin.. Adenocarcinoma of colon at the right and normal colon at left A 45-year-old man with a family history of colon cancer undergoes a screening colonoscopy. No invasive carcinomas are identified, but two small pedunculated polyps are removed and one sessile polyp measuring 5 mm in diameter is biopsied. 1- What is the most likely diagnosis? 2-What are the syndromes that could predispose this individual to colon cancer? 3-What other dietary factors could play a role in the development of colon cancer? Thank you