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Pathology of Gastric Carcinoid Tumours

Dr Sampurna Roy MD

 

 

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Gastric carcinoids are rare tumours.

Clinical setting:

Type I  - Associated with chronic atrophic gastritis with or without pernicious anemia.

In autoimmune gastritis progressive destruction of the specialised parietal and chief cell zone leads to atrophy, intestinal metaplasia , hypochlorhydria and hypergastrinemia.

Type II - In Zollinger Ellison syndrome, particularly in patients associated with multiple endocrine neoplasia type 1.        
   
Type III - Sporadic tumours

- Not related to hypergastrinemia

- In the antrum or corpus

- Larger lesion, may be ulcerated.

- May have an aggressive course.

 

Endocrine cell hyperplasia :

Characterized by increased numbers of cells/unit area of the mucosa.


Types:

I  G-cell hyperplasia: Associated with increased number of G -cells in the antrum,hypergastrinemia and ulcerogenic syndrome resembling Zollinger Ellison syndrome.

II ECL cell hyperplasia:

Types of Gastric Carcinoids:

I  Tumour composed of G-cells (gastrinoma)

II  Tumour cells are composed of enterochromaffin-like (ECL) cells in the oxyntic mucosa. 

Hypergastrinemia plays an important role in the pathogenesis of gastric carcinoids.

MEN type 1 gene locus may also be involved in the pathogenesis.

G-Cell Hyperplasia and G-Cell Carcinoids:

- G-cell hyperplasia (increased number of G-cells in the middle and lower third of antral glands).

- Progress to form micronodular G-cell clusters.

- Finally form  G-cell carcinoids (Gastrinoma).

- These are usually solitary lesions.

- Located in the gastric antrum.

- G-cell hyperplasia should be distinguished from G-cell carcinoids.

- Gastrinomas are commonly present in the pancreas and duodenum.

Hyperplasia of Enterochromaffin-Like (ECL) Cells and Carcinoids composed of ECL Cells:

- There is corpus ECL cell hyperplasia following antral G- cell hyperplasia. Gastrin has a stimulatory action on ECL cells.

-  ECL cell are scattered singly or in clusters. (upto 3 cells / glands).

-  Linear hyperplasia along glandular basement membrane.

-  Followed by formation of solid micronodular endocrine cell nests ( microcarcinoids ). These are 100 - 150 mm in diameter.

-  Micronodules enlarge show cytological atypia  and break basement membrane.

-  Finally these nodules form overt carcinoid tumour. These have a lobular or trabecular pattern and are more than 0.5 mm in diameter. 

Features of ECL Cell Carcinoids: 

- Most common type of gastric carcinoid.

- These are usually multiple lesions.

- Distributed  throughout  the fundus.

- Non- argentaffin but strongly argyrophilic.

- ECL cell carcinoid  in chronic corpus gastritis (autoimmune) are usually small (less than 1cm in diameter) and rarely metastasize.

- Virtually never lethal.

- Never produce clinical hypersecretion syndrome.

- May regress spontaneously or following antrectomy.

- Treated by local excision or endoscopic polypectomy

- Gastrectomy is indicated in rare cases where tumours are larger (more than 2cm) and numerous or small tumours with angioinvasion.

Features of ECL Cell Carcinoids: 

- Most common type of gastric carcinoid.

- These are usually multiple lesions.

- Distributed  throughout  the fundus.

- Non- argentaffin but strongly argyrophilic.

- ECL cell carcinoid  in chronic corpus gastritis (autoimmune) are usually small (less than 1 cm in diameter) and rarely metastasize.

- Virtually never lethal.

- Never produce clinical hypersecretion syndrome.

- May regress spontaneously or following antrectomy.

- Treated by local excision or endoscopic polypectomy

- Gastrectomy is indicated in rare cases where tumours are larger (more than 2cm) and numerous  or small tumours with angioinvasion.

Gross features of Gastric Carcinoids:

- Small polypoid, well circumscribed raised lesion covered by mucosa.

- Larger lesions infiltrate through the full  thickness of the stomach wall.

- Cut surface has a yellow-gray appearance.
 

Microscopic features:

-Microglandular or trabecular growth pattern.

-Composed of small regular cells with finely granular cytoplasm.

-Clear cell variant has been reported.

-Round or oval nuclei.

-Minimal pleomorphism.

-Mitoses are scanty. Necrosis is usually absent.

-Retraction artifact noted around nests of cells.

 

Capella C et al. 1995. Revised classification of neuroendocrine tumours of the lung, pancreas and gut. 

Benign:  

Limited to mucosa and submucosa. No angioinvasion : Less than 1cm.

Borderline: 

-Limited to mucosa & submucosa.

-Angioinvasion (+) : Less than 1cm

-Angioinvasion  (-) : 1  to  2 cm

Low Grade malignant:  

-Any functioning tumour.

-Invade beyond submucosa.

-Angioinvasion: (+)   :   1  to 2 cm

-Angioinvasion:  (-) :  More than 2 cm

High Grade Malignant: 

Atypical carcinoid / small cell carcinoma.                                               

Atypical carcinoids are characterized by :

- infiltrative growth pattern.

- presence of vascular invasion.

- necrosis.

- nuclear pleomorphism.

- hyperchromasia.

- mitotic activity more than 2 per 10 HPF.

 

Immunohistochemistry :

The tumour shows immunopositivity for:

- Neuron specific enolase

- Chromogranin A

- Synaptophysin

- Leu 7

- PGP 9.5

- Carcinoembryonic antigen in some cases

 

Further reading:

Morphological, molecular, and prognostic aspects of gastric endocrine tumors.

Endocrine cell growths in atrophic body gastritis. Critical evaluation of a histological classification. 

Carcinoid tumors of the stomach in atrophic autoimmune gastritis: classification, differential diagnosis and prognosis.

Hyperplastic, dysplastic, and neoplastic enterochromaffin-like-cell proliferations of the gastric mucosa. Classification and histogenesis.

Enterochromaffin-like (ECL) cells and their growths: relationships to gastrin, reduced acid secretion and gastritis.

Gastric endocrine cell hyperplasia and carcinoid tumors in atrophic gastritis type A.

Gastric carcinoids. An immunohistochemical and clinicopathologic study of 104 patients.

Pattern of gastric endocrine cells in microcarcinoidosis--an immunohistochemical study of 14 gastric biopsies.

 

 

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Gastric Pathology - Home Page  

 

 

Dr Sampurna Roy  MD

Consultant  Histopathologist (Kolkata - India)


 

 

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