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Cross‐section of a colonic diverticulum shows a central lumen (2) with surrounding mucosa.The mucosal layer (1) is attenuated and lacks a muscle layer. The narrow neck (3) of thediverticulum may become eroded, suffer mechanical damage and result in bleeding.
What is this? What do the two images represent?
- Adenomatous polyp
- 1: Adenomatous polyp, also calledtubular adenoma, will often beattached to the intestinal wall by asmall stalk.
- 2: In cross‐section, the adenomatouspolyp has a crowded, disorganized gland structure contrasting with thenormal underlying colonic mucosa.Goblet cells are less numerous and thecells lining the glands of the polyphave hyperchromatic nuclei. This adenoma is still well‐differentiated,without invasion of the stalk, and is considered benign.
What is this? What are the numbers? Where are most of these found? How are they classified?
- Hyperplastic polyp
- 1: Cross‐section of a hyperplastic polyp. This magnification shows the polyp is composed of a well organized colonic mucosa at the periphery and contains hyperplastic glands andsmooth muscle bundles toward the center.
- Found: Most hyperplastic polyps are found in the distal regions of the large intestine and rectum.
- 2: Colorectal polyps are typically classified bytheir behavior (i.e. benign vs. malignant)- benign (e.g. hyperplastic polyp), pre‐malignant (e.g. tubular adenoma), or malignant (e.g. colorectal adenocarcinoma)
- 3: hyperplastic glands
- 4: smooth muscle bundles
What are these? What disease do you see these in?
- 1: Pseudopolyps are seen here in a case of severe, unmanaged ulcerative colitis. Much of the remaining mucosa has been ulcerated away andis hyperemic. Pseudopolyps formfrom repeated cycle of ulceration,alternating with the deposition of granulation tissue during the healing phase. This results in the development of raised areas of inflamed tissue that resemble polyps.
- 2: View of active ulcerative colitis by colonoscopy, but not so extensive as to produce pseudopolyps.
What is this? What is its tissue origin and why is it unique? Where does it occur? What cells give rise to it and what are their functions?
- GIST(GASTROINTESTINAL STROMAL TUMOR)
- Gastrointestinal stromal tumors (GIST) are one ofthe most common mesenchymal tumors of the GI tract accounting for 1‐3% of all GI malignancies.
- Origin: connective tisse (GISTs are considered sarcomas), which is different because most most GI tumors that are of epithelial origin (carcinomas).
- Occurs: About 70% of GISTs occur in the stomach, 20% in the small intestine and less than 10% in the esophagus.
- Come from: GISTs are thought to arise from interstitial cells of Cajal that are part of the autonomic nervous system of the intestine. Recall that these cells serve a pacemaker function in controlling motility
What disease is this? What do the arrows represent?
- Ulcerative Colitis
- 1: Inflammation that occurs during episodes of ulcerative colitis is confined primarily to the mucosa llayer.
- 2: Here, the mucosa adjacent to normal tissue is eroded by an ulceration.
- 3: At higher magnification, neutrophils infiltrate the mucosal layer.
- 4: Goblet cells become absent from thecolonic mucosal epithelium.
What is this? What disease led to this?
- ADENOCARCINOMA ACCOMPANYING ULCERATIVE COLITIS
- Over time, ulcerative colitis increases the risk for developing adenocarcinoma. Here, normal glands (1) are seen at the left, but glands at the right show evidence of dysplasia (2), the first indication that there is a progression towards neoplasia.
What disease is this? What causes it? What do the arrows indicate?
- HIRSCHSPRUNG’S DISEASE
- Hirschsprung’s disease results from an incomplete migration of neural crest cells(enteric ganglion cells) during fetal development of the large intestine. The affected segment of the colon, most oftena short segment of the distal colon, fails torelax, causing an obstruction.
- A normal myenteric plexus in the gut has large round ganglion cells with adjacent small flattened Schwann cells that haveflattened nuclei.
- Arrows: In patients with Hirschsprung’s disease, ganglion cells in the sub‐mucosa are absent, but they do retain flattened Schwann cells. This section is from abiopsy of the rectum.