Stomach carcinoma

Stomach carcinoma, also carcinoma of the stomach and gastric carcinoma, is an epithelial derived malignant tumour that arises from the stomach.

Stomach carcinoma
Diagnosis in short
Stomach signet ring cell carcinoma. H&E stain.
Subtypes	Lauren classification: intestinal type, diffuse type; WHO classification: papillary carcinoma, tubular carcinoma, mucinous carcinoma, signet-ring carcinoma, undifferentiated carcinoma, adenosquamous carcinoma
LM DDx	gastric xanthoma, neuroendocrine tumour, metastatic carcinoma (e.g.pancreatic ductal adenocarcinoma, gastric dysplasia
Stains	CK7 +ve, CK20 -ve/+ve
Site	stomach
Syndromes	hereditary diffuse gastric cancer, familial adenomatous polyposis, Lynch syndrome, Peutz-Jeghers syndrome, Li-Fraumeni syndrome, Gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS)
Prevalence	uncommon
Endoscopy	+/-linitis plastica (diffuse carcinomas), +/-ulcer with heaped (raised) edges (intestinal carcinomas)
Prognosis	usually very poor
Clin. DDx	benign ulcer, other gastric tumours
Treatment	surgery if feasible

Many gastric carcinomas form glands and can thus be called gastric adenocarcinoma or adenocarcinoma of the stomach.

General

Epidemiology:

• Prognosis is often poor as it is discovered at a late stage.
• Higher prevalence in countries in the far east (e.g. Japan) - thought to be environmental, e.g. diet.

Risk factors:

• Associated with helicobacter infections, i.e. Helicobacter gastritis.
• Alcohol - heavy use.
• Genetic syndromes:
  • Hereditary diffuse gastric cancer.
  • Familial adenomatous polyposis.
  • Peutz-Jeghers syndrome.
  • Lynch syndrome.

Note:

• Possible association with tobacco use - dependent on the study.

Treatment:

• Surgical excision.
  • Proximal tumours may require a complete gastrectomy as the stomach is innervated from its proximal part.

Classification

• Two different classification schemes.
  • Lauren - two types:
    • Intestinal type (mass forming).
    • Diffuse type (infiltrative).
  • WHO classification - 6 subtypes for adenocarcinoma:
    1. Papillary carcinoma.
    2. Tubular carcinoma.
    3. Mucinous carcinoma.
    4. Signet-ring carcinoma.
    5. Undifferentiated carcinoma.
    6. Adenosquamous carcinoma.

Lame memory device STOMACH:

• Signet ring, Tubular, Oh papillary, Mucinous, Adenosquamouas, Crappy High grade (Undifferentiated).

Gross

Location:

• Large carcinomas preferentially involve the lesser curvature.
• Ulceration with heaped (raised) edges.
  • Appearance of the typical intestinal type tumour.
• Diffuse wall thickening with loss of the rugae - called linitis plastica.
  • Typically due to diffuse carcinoma.

Main DDx of gastric ulcer:

• Peptic ulcer disease - have a "punched-out" appearance: sharp edge, no granularity of surrounding mucosa.

Images

• 

  Linitis plastica - endoscopic image. (WC)

• 

  Ulcerating gastric carcinoma. (WC)

• 

  Ulcerating gastric carcinoma. (WC)

Microscopic

Features - variable, either of the two following:

1. "Typical adenocarcinoma":
   • Gland-forming lesion that infiltrates into the lamina propria or beyond.
   • Nuclear pleomorphism - common.
2. +/-Signet ring carcinoma.
   • Scattered single cells in the lamina propria or beyond with:
     • Abundant cytoplasm containing one large (mucin-filled) vacuole.
     • A peripheral nucleus (displaced by the vacuole).

DDx:

• Gastric xanthoma - may mimic signet ring cell carcinoma.
• Neuroendocrine tumour - esp. for poorly differentiated; no gland formation.
• Metastatic carcinoma.
  • Pancreatic ductal adenocarcinoma.
• Gastric dysplasia.

Grading

• Moderately differentiated >=50 % glands.^{[citation needed]}
• Poorly differentiated >=50% no glands (sheeting or nests).

Images

• 

  Gastric adenocarcinoma. (WC)

• 

  Gastric SRC - PAS stain. (WC)

www:

• Gastric adenocarcinoma - several images (upmc.edu).

Stains

• Mucicarmine +ve.

IHC

• AE1/AE3.
• CK7 +ve.
• CK20 -ve, occasionally +ve.
• CDX2 +ve.

Others:

• p53 +ve in upto 75% of cases.

Molecular

• May have HER2 over expression - more common in intestinal-type tumours.
  • Poor prognosis - like in breast cancer.
  • Scoring system different than in breast cancer - complete membrane staining is not required.

Staging

• Sixteen (or more) lymph nodes should be assessed (as per the 7th Ed. of the UICC/AJCC staging).
  • The 5th Ed. of the UICC/AJCC staging manual stated 15 lymph nodes.

Sign out

Biopsy

Intestinal type

Stomach, Biopsy: 
- INVASIVE ADENOCARCINOMA, INTESTINAL TYPE, moderately differentiated. 
- Gastric mucosa with intestinal metaplasia. 

Comment:
The tumour stains as follows:
POSITIVE: CK7, CDX2.
NEGATIVE: CD20.

HER2 testing has been ordered and will be reported as an addendum.

STOMACH, BIOPSY:
- INVASIVE ADENOCARCINOMA, INTESTINAL TYPE, MODERATELY DIFFERENTIATED.
- Gastric mucosa with moderate chronic active inflammation and extensive
  intestinal metaplasia.
- Benign small bowel mucosa with erosions.

GASTRIC ULCER, BIOPSY:
- INVASIVE ADENOCARCINOMA, INTESTINAL-TYPE, MODERATELY DIFFERENTIATED.

Diffuse type

STOMACH, BIOPSY:
- INVASIVE ADENOCARCINOMA, DIFFUSE TYPE.

COMMENT:
A pankeratin immunostain demonstrates single (infiltrating) epithelial cells in the
lamina propria.

Micro

The tumour consists of single cells with abundant foamy-appearing cytoplasm and eccentric nuclei with mild nuclear atypia.

Poorly differentiated

 GASTRIC ULCER, BIOPSY:
- INVASIVE ADENOCARCINOMA, POORLY-DIFFERENTIATED.

See also

• Stomach.
• Siewert classification.