Last updated on March 10, 2020 at 15:37
Polyps can also occur in the stomach. There are many types of polyps, and some of them are not neoplastic, and is typically seen in some diseases.
- Hyperplastic polyps
Almost all polyps in the stomach tend to be hyperplastic polyps, and its associated to chronic gastritis, both with or without H. pylori.
The polyps are usually 1-2 cm big and located in the antrum as multiple polyps. The risk of developing into malignancy is low, but it increases if the polyps are bigger than 2 cm.
- Fundic gland polyps
Fundic gland polyps can occur sporadically or in persons with familiar adenomatous polyposis (FAP) and are usually located in the fundus and the corpus of the stomach. These polyps are well circumscribed and are composed of dilated irregular glands which are lined by parietal and chief cells. The interesting part is that their occurrence has increased due to increased use of proton-pump inhibitor therapy, which will result in the increase of gastrin release and glandular hyperplasia by gastrin.
These polyps usually don’t develop into something malignant, except if the patient has FAP since the polyps appear in a younger age and more numerous, with some dysplasia.
They are also mostly asymptomatic, but some patients may experience nausea, vomiting and pain.
- Hamartomatous polyps
These kinds of polyps consist of disorganized cells and tissue which are usually found at the site of where the polyps lie. They are mostly part of polyposis syndromes, like Peutz-Jeghers syndrom, Cronkhite-Canada syndrome, Juvenile Polyposis and Gardner-syndrome
- Inflammatory fibroid polyp
These polyps are basically submucous granulomas with infiltration of eosinophils, and they have a round whitish appearance with a gum-like consistency.
The polyps consist of a mixture of stromal and inflammatory cells, are rich in vessels and a matrix full of collagen.
- Xanthoma of the stomach
Recall that a xanthoma is a “lipid island”, which can also be found on the eyelids and around the eyes. Having them in the stomach is most common in Japan and can be due to bile reflux. They have no significance clinically.
Adenomas in the stomach
The adenomas are considered rare, and the chances of getting them increase with age and with the different populations. Men have also 3 times higher risk of getting them. Adenomas mostly occur in patients with a history of chronic gastritis with atrophy and intestinal metaplasia and are usually located in the antrum. Since they show a morphology similar to intestinal columnar epithelium, we say that they show an epithelial dysplasia, and they can be graded by the Vienna classification (not included here).
The risk of it turning into adenocarcinoma increases when the lesions are bigger than 2 cm.
Carcinoma of the stomach
Adenocarcinoma of the stomach is the most common cancer found in the stomach and accounts for 90% of them. The early symptoms are similar to those of chronic gastritis with dyspepsia (indigestion), dysphagia and nausea, and can be confused with it until the patient reaches the later stages with weight loss, different bowel habits, anaemia and haemorrhage.
Like for adenomas, the incidence is higher in older men and in countries like Japan, Chile and Eastern Europe. In total, the incidence has declined lately. The mortality of this cancer is however high in the countries with low prevalence because screening is not performed as often as in high-prevalence countries. Therefore, the cancer is often discovered too late.
- Mutations in the CDH I, p53 and APC genes
- H. pylori infection (only intestinal type, not diffuse type)
- Epstein-Barr virus
- Atrophic gastritis
- Previous gastrectomy
- Intestinal metaplasia
The carcinoma is usually located in the antrum, followed by corpus and fundus. The carcinoma can also very often be found in overlapping areas.
How do we classify the cancer? We can use the Lauren classification which separates the gastric cancers into intestinal and diffuse types according to their location in the stomach and their gross and histological morphology.
The intestinal type has glandular structures. It has a better prognosis than the diffuse type. This type can be classified as high grade or low grade depending on whether the glandular structures show poor differentiation or well differentiation, respectively.
The diffuse type has a special cell type called signet ring cells spread diffusely across the mucosa. These cells have their nuclei compressed on the periphery of the cell, and they have large mucin-containing vacuoles in the cytoplasm. They can be hard to find on biopsy because they’re so diffusely spread. This type is more aggressive and has a worse prognosis than the intestinal type.
Ming’s classification can tell us how the cancer is expanding. They can either have an expansive (exophytic) or infiltrative growth.
What are the differences between an early and an advanced gastric cancer? Per definition, “early” gastric cancer infiltrates no deeper than the submucosa but even early cancer can give metastasis to the lymph nodes, while “advanced” cancers infiltrate the muscularis propria and deeper.
Macroscopically, we can see 4 different types according to the Bormann classification:
- Polypoid type – Protrudes into the lumen like a polyp
- Fungative type – Protrudes and has ulcerative surface
- Ulcerative type – Non-protruding with ulcerative surface
- Diffuse growth type – Diffusely thickened gastric wall (linitis plastica)
This carcinoma often metastasizes to the regional lymph nodes like:
- On the greater and lesser curvatures
- Greater and lesser omental lymph nodes
- Cardiooesophageal lymph nodes
- Gastroduodenal lymph nodes
It can also spread haematogenically via the portal system and to the peritoneal surfaces.
Other tumors of the stomach
- Gastrointestinal stroma tumor (GIST)
This type of tumor is the most common mesenchymal tumor from the Cajal-cells that express CD117, also called C-kit. It can occur anywhere in the GI-tract, but is most commonly found in the stomach, followed by the duodenum.
The C-kit gene, which encodes for a tyrosine kinase, is often mutated in the patients with GIST. The incidence of this tumor is also highest in men in their sixties.
Morphologically, the tumor can either be submucous, subserous or intramural. The submucous one is often ulcerated and polypus. In histology, elongated spindle cells, epithelioid and a mix between these can be distinguished. It is also often myxoid, which means that substances that resemble mucus can be seen. To treat this, a surgical resection is needed.
The GIST can metastasize to the peritoneum through seeding and to the liver via blood.
- Other tumors include:
- Gastrinoma (Zollinger-Ellison syndrome)
- Granular-cell tumor
- Kaposi sarcoma
- Malignant lymphoma, discussed in detail later in this topic.
But these types are very rare!
- Metastases from other organs with cancer that can appear in the stomach:
- Lobular carcinoma of the breast
Primary lymphomas of the stomach
The lymphomas can arise in every tissue, but it’s most commonly found in the stomach. However, it’s still one of the rarest malignancies that you can have there. The lymphomas include:
- MALT lymphoma
- DLBCL – diffuse large B-cell lymphoma
- Mantle cell lymphoma
We will discuss the MALT lymphoma and DLBCL briefly.
- MALT lymphoma of the stomach
MALT lymphoma is a cancer originating from B-cells in the MALT. The risk factor is H. pylori, which secrete the endotoxin CagA that leads to B-cells proliferation and autoreactive B-cells. These events eventually lead to a lymphoma. Treatment is by treating the H. pylori infection, which causes the lymphoma to regress.
This type occurs in middle-aged or older patients and dominates in females.
- DLBCL – diffuse large B-cell lymphoma
DLBCL can either be primary, or secondary which follows the transformation of a MALT-lymphoma. This is the most common type of lymphomas in the stomach, and 50 % of the patients that have are also positive for H. pylori.
4. Inflammatory and ulcerative disorders of the stomach
6. Malformations of the small intestine. Malabsorption. Tumors of the small intestine