INSTRUCTORS ONLY

GI Path Lab 1

Areas of Concentration

• Normal gastrointestinal tract, liver, pancreas and biliary tract

• Diseases of the esophagus

• Diseases of the stomach

Upon completion of this exercise, you should be able to:

1. Recognize the normal anatomy of the gut, liver, pancreas, and biliary tract.

2. Recognize metaplastic columnar epithelium in the esophagus and know its name and meaning.

3. Recognize the histologic differences between an adenocarcinoma and a squamous cell carcinoma. Recognize adenocarcinoma precursors.

4. Recognize the two most important histologic types of chronic gastritis, Helicobacter pylori type and the atrophic type, and other gastric conditions to which they may predispose.

5. Understand what makes an ulcer chronic rather than acute.

Slide 84 [WebScope] [ImageScope]

Esophagus: Barrett’s Mucosa with Dysplasia

Some of the slides contain slightly inflamed gastric mucosa at one end. Extending from that all the way to the other end is a columnar mucosa that has scattered deep mucus-producing glands and superficial elongated tubules, some of which extend from the surface to the base of the mucosa. Some of these tubules are lined by gastric-type surface epithelium with apical pink mucous vacuoles. Other tubules have intestinal-type goblet cells with big blobs of blue-staining mucus, evidence of intestinal metaplasia. Still other tubules have very little mucus of any type and contain epithelium with large, stratified nuclei which, in a few areas, are hyperchromatic and even vary in size and shape. These latter features are those of dysplasia.

1. What is the cause of Barrett's mucosa?

2. What are its classical symptoms?

3. What is dysplasia?

4. Why is dysplasia important in patients who have Barrett's mucosa?

5. What is being done to prevent Barrett's carcinomas from developing or to detect them when they are small and not likely to kill the patient?

6. How do most Barrett's carcinomas present clinically?

7. Why do you think this esophagus was removed?

Slide 77 [WebScope] [ImageScope]

Squamous Cell Carcinoma of the Tongue (to be used as a surrogate for squamous cell carcinoma of the esophagus; pretend that this is the esophagus!)

This squamous cell carcinoma of the esophagus invades deeply, has a variety of patterns and is present in dilated spaces that are lymphatics.

1. What are the risk factors commonly associated with this cancer in Western societies?

2. What has happened to the incidence of this cancer in the United States over the past 30 years?

3. What histologic abnormality preceded the development of this invasive carcinoma?

4. What feature correlates best with prognosis in all types of esophageal carcinoma?

Slide 83 [WebScope] [ImageScope]

Chronic Active Gastritis - Helicobacter pylori Type

The normal gastric mucosa has very few inflammatory cells. This mucosa, in contrast, is intensely inflamed. First, there are many lymphoid nodules at the base of the mucosa, some with hyperplastic germinal centers. Second, there is intense plasmacytosis in the superficial part of the mucosa, in the region of the pits and the superficial glands. In fact, some patches of lamina propria are stuffed with plasma cells. Finally, in some of the sections, there are a few neutrophils within the epithelium of the neck regions and in the surrounding lamina propria. This gastritis is typical of the type caused by H. pylori. We rarely see the organisms in a resected specimen such as this, perhaps as a result of treatment with antibiotics prior to the operation, or because in resection specimens the pathologist tends to wash the mucosa in order to see it better, and washing removes the mucus coat in which the organisms usually reside.

1. Who gets Helicobacter pylori gastritis? Is this gastritis a clinical disease with symptoms?

2. Why is identification of the organisms whether by biopsy or by other means important?

3. Are there any other ways (other than by looking at the stomach microscopically) to prove that an individual is infected with this organism?

4. What other diseases may result from longstanding H. pylori infection?

Slide 22 [WebScope] [ImageScope]

Stomach: Peptic Ulcer

The ulcer is the broad area that has no mucosa.

1. What is the most common cause of gastric peptic ulcers? Of duodenal peptic ulcers? What is the second most common cause?

2. How deep does this ulcer extend??

3. What are potential complications?

4. Is this ulcer acute or chronic? How do you know?

5. What is going on at the ulcer edges?

6. Is this ulcer a high-risk cancer precursor?

Slide 85 [WebScope] [ImageScope]

Stomach: Early Gastric Carcinoma

This is gastric mucosa in which the mucus glands take up approximately half of the entire thickness, indicating that it is either antral or cardiac mucosa. In some sections, at one end, there is a peculiar mucosa with villous-like surface projections and goblet cells with bluish mucus scattered among the more typical gastric surface cells that contain apical pink-staining mucus. This is intestinal metaplasia, one of the histologic changes in atrophic gastritis. It resembles the Barrett's mucosa of Slide 84. In fact, it has similar dysplastic changes.

In the center of the slide, the epithelium becomes more disorganized with hyperchromatic and pleomorphic nuclei and numerous mitotic figures. At the base of the mucosa, this epithelium invades through the fibers of the muscularis mucosae. In some slides, nests of carcinoma are found within lymphatics in the superficial submucosa. The deeper submucosa, muscularis propria and subserosa of the wall of the stomach are normal.

1. Why is this called "early gastric cancer"?

2. How can gastric cancer be detected at this stage?

3. Is this a common stage of gastric cancer in the United States? In Japan?

4. What is the cause of most cases of gastric carcinoma?

The answers to the path lab questions will be posted approximately 48-72 hours after the lab sessions. These are abbreviated answers, not a full discussion of the topics. You can find them in the M2 CTools site resources. In the folder for each sequence the will be a folder called 'Path Lab Resources'