Molavi Chapter 7 - Stomach and Duodenum

Question 1

Two types of gastric mucosa

Answer 1

Antral (mucinous or protective, shown in B). Thinner muucosa with mucinous glands and overlying foveolar epithelium.

Oxyntic (secretory). Thick mucosa with secretory cells including the parietal and chief cells and an overlying foveolar epithelium.

Transitional mucosa is where the two overlap and features are mixed.

Question 2

Foveolar epithelium

Answer 2

Lining of the stomach

Stains bright pink with PAS/AB

Question 3

Cells within an oxyntic gland

Answer 3

Question 4

Cells within a pyloric gland

Answer 4

Question 5

Intestinal metaplasia

Answer 5

When the epithelium is lined with occasional goblet cells.

Marker of chronic irritation in the stomach.

Note that the goblet cells should be interspersed. You will probably never see just back-to-back goblet cells on the stomach epithelium.

Question 6

Active vs Inactive gatsritis

Answer 6

Neutrophils in the stomach epithelium indicate “active” inflammation (by convention “active” instead of “acute” in the stomach)

If you have only mononuclear cells, you have “inactive” chronic gastritis

If you have both, you have “active chronic” gastritis

Question 7

Active chronic gastritis and lymphoid follicles in the gastric mucosa typically indicate ___

Answer 7

Active chronic gastritis and lymphoid follicles in the gastric mucosa typically indicate H. pylori infection

Question 8

Active or inactive chronic gastritis with a granuloma

Answer 8

Crohn’s disease is most likely

Question 9

Answer 9

Chemical gastritis in the antrum

Note the foveolar hyperplasia with a corkscrew-papillary appearance, low-power blue appearance, and prominent thin strands of smooth muscle between glands.

May be caused by bile reflux or pill-induced chemical irritation.

Question 10

Answer 10

Autoimmune gastritis with gastric atrophy

Atrophy is indicated by intestinal metaplasia and inflammation.

There is replacement of secretory glands by mucinous, antral-type glands (2).

Some residual oxyntic cells are visible (3).

Question 11

Gastric atrophy and what causes it

Answer 11

Gastric atrophy is loss of glands in the stomach, in any region.

True atrophy will have intestinal metaplasia and inflammation.

Two principal causes are H. pylori and autoimmune metaplastric atrophic gastritis (which may progress to pernicious anemia).

Question 12

Disease course of autoimmune metaplastic atrophic gastritis

Answer 12

• Autoimmune response against parietal cells in the gastric body
• Progression to gastric atrophy
• Loss of intrinsic factor due to parietal cell destruction (pernicious anemia)
• Compensastory antral gastrin-cell response with hypergastrinemia
• ECL cell hyperplasia which may progress to microcarcinoids or tumorlets
• “Antralized” atrophic oxyntic mucosa due to replacement of oxyntic glands.

Question 13

Presence of lymphoid follicles in the gastric mucosa in the setting of gastric atrophy suggests. . .

Answer 13

. . . H. pylori, NOT autoimmune metaplastric atrophic gastritis

Question 14

In the setting of chronic autoimmune gastritis with “antralized” atrophic oxyntic mucosa and true antral mucosa, how can you tell if you biopsied the right site?

Answer 14

Only the true antrum will have G-cells.

So, a gastrin stain can differentiate “antralized” from “antral” mucosa.

Question 15

Answer 15

DLBCL of the stomach

Truly “sheets” of large B cells.

Question 16

How can you differentiate MALT lymphoma from regular old MALT?

Answer 16

Only in lymphoma will you have lymphoepithelial lesions, which are collections of lymphocytes that appear to be eating glands.

MALT lymphoma cells also have a characteristic morphology.

Question 17

Answer 17

MALT lymphoma

MALT lymphoma is a marginal zone-type lymphoma with monocytoid appearance (fried-egg-like cells, small round nuclei with a halo of clear cytoplasm).

Lymphoepithelial lesions are present (inset). Here the glands look like little more than islands of pink cytoplasm.

You can confirm with immunostains: CD20+ CD43+. T cells will also stain CD43+, so you should subtract them out with a CD3 stain. Usually most cells will be either CD20+CD43+ or CD3+CD43+, as most lymphocytes in chronic gastritis are T cells.

Question 18

MALT lymphoma immunophenotype

Answer 18

CD20+CD43+

CD3-

Question 19

Chronic gastritis immunophenotype

Answer 19

CD3+CD43+

CD20-

Question 20

Answer 20

Gastric amyloidosis

Note the abundance of pink, amorphous material in the lamina propria. Give it the good-old Congo red stain to confirm.

A potential cause of gastroparesis in a patient with the right risk factors.

Question 21

Answer 21

Fundic gland polyp

Most common type of polyp found on upper endoscopy.

These polyps look like oxyntic mucosa, but with occasional cystically dilated glands (circled). They are common in older individuals.

They are associated with chronic PPI use. Also, multiple fundic polyps may occur in a young individual with FAP. There is thought to be a connection to superphysiologic levels of gastrin, which can act as a hyperplastic and hypertrophic factor for parietal cells in oxyntic glands.

Question 22

Answer 22

Hyperplastic gastric polyp

Characterized by elongated or cystic foveolar pits with mild inflammation. Usually associated with background gastritis and may have intestinal metaplasia.

Glands reminiscent of chemical gastritis with an elongated corkscrew appearance may be seen.

Question 23

Answer 23

Foveolar-type gastric adenoma

By definition, gastric adenomas have at least low-grade dysplasia (like an intestinal tubular adenoma).

Note the foveolar-like epithelium

Question 24

Answer 24

Intestina-type gastric adenoma

By definition, gastric adenomas have at least low-grade dysplasia (like an intestinal tubular adenoma).

Note the presence of goblet cells.

Question 25

Answer 25

**Intestinal-type gastric adenocarcinoma** Note its morphological similarity to colon cancer, hence the name. Often found in association with gastric atrophy and intestinal metaplasia.

Question 26

Answer 26

**Diffuse-type gastric adenocarcinoma** May creep through the entire stomach and cause **linitus plastica** (rigid, non-distendable stomach). Often has a **signet-ring cell** morphology. These cells can look like foamy macrophages and hide on low-power. For this reason every stomach biopsy should get a once-over on high power. When they are there, the more you look the more you will see.

Question 27

Answer 27

**Gastrointestinal stromal tumor (GIST)** There is just *way* too much stroma here. On high power you might see **multiple mitotic figures** or **cytoplasmic/paranuclear vacuoles**. This tumor arises from the **interstitial cells of Cajal.** They are driven by **c-Kit (CD117)** and also **stain for DOG1**. Their malignant potential is assessed by size, location, and mitotic rate. DDx includes schwannoma (S100+), leiomyoma (smooth muscle markers), and heterotopic pancreas (pancreas tissue that just got lost).

Question 28

Normal duodenal histology

Answer 28

Question 29

Brunner glands

Answer 29

Normal mucous glands of the muscularis mucosa in the duodenum Stain bright in PAS/AB Only appear in the duodenum. They disappear in the transition to the jejunum.

Question 30

Rules of a healthy duodenum

Answer 30

1. The villi should be 3x as tall as the crypts are deep 2. There should not be any collections of lymphocytes within villi 3. There should be no neutrophils in the epithelium

Question 31

Answer 31

Chronic peptic duodenitis Note the **foveolar metaplastic change** at the tips of the villi (arrow). There is increased **chronic inflammation in the lamina propria** and **Brunner gland hyperplasia** (arrowhead). Sometimes neutrophils may also be seen in the epithelium. Be wary of **gastric heterotopia** -- misplaced nodule of totally normal gastric tissue within the duodenal wall.

Question 32

Rule of thumb for Celiac's disease

Answer 32

The earliest change in Celiac's disease is prominent intraepithelial lymphocytes (IELs), long before there is villous blunting: **Over 40 IELs / 100 enterocytes (roughly 1 villus-worth)** is considered diagnostic of a malabsorptive pattern. However, whether this malabsorption is *due to* Celiac's disease will require supportive serology and/or clinical picture.

Question 33

Answer 33

Duodenal giardiasis You can see them if you squint! Those aren't shed epithelial cells. Zoom in to high power to confirm.

Question 34

Answer 34

Strongyloides There are tiny worm bodies visible within the duodenal crypts.

Question 35

Answer 35

**Duodenal tubular adenoma** As in the colon, characterized by **low-grade dysplasia** with **crowded and elongate nuclei** and **loss of mucinous differentiation.**

Question 36

Answer 36

Duodenal carcinoid tumor (aka well-differentiated neuroendocrine tumor)

Question 37

G cells

Answer 37

Appear as **haloed neuroendocrine cells** within **pyloric glands**

Question 38

Small intestinal bacterial overgrowth on histology

Answer 38

Has a comparable pattern to Celiac's disease with villous blunting and intraepithelial lymphocytes.