Adenocarcinoma- histological (Courtesy of BioMed Image Archive)
  • Adenocarcinoma is the most common gastric neoplasm in small animals.
    • This is a tumour of the mucosal epithelium.
  • These are genreally found in the fundus (particularly along the lesser curvature), and in the pylorus.
  • There are two main internal appearances of gastric adenocarcinoma, both of which show thickened, oedematous, pale and firm tissue:
    Adenocarcinoma- gross (Courtesy of BioMed Image Archive)
    1. A diffuse infiltration of gastric mucosa by neoplastic glandular epithelial cells.
      • Causes a diffuse rugal thickening.
    2. A more solitary lesion that is seen as a thick plaque-like lesion
      • Generally has a central erosion/ulceration of the tumour tissue.
        • Distinguishable from a peptic ulcer as the edges of the eroded area are raised and thickened (tumour tissue).
  • The external appearance of an affected stomach can include thickening of the draining lymphoid vessels due to tumour infiltration ('cording of the lymphatics') and evidence of a scirrhous reaction to the carcinoma.
  • Adenocarcinomas are locally aggressive and spread via the lymphatics to the lymph nodes, lung, liver and adrenal glands.

Intestinal

  • An intestinal adenocarcinoma is a malignancy of epithelial cells from the intestinal mucosa.
  • Found in both the small and large intestines
  • Species affected:
    • Fairly common in dog and cat.
    • Seen related to bracken ingestion in the older sheep.
    • Occasionally occur in horses.
  • These tumours usually grow away from the mucosa, down through the muscularis mucosae and into the submucosa, muscular layers and the serosa.
    • They may, however, project into the lumen.
  • Intestinal adeocarcinomas may take an annular form.
    • This may result in stenosis of lumen
      • Muscle proximal to the lesion becomes hypertrophied and dilated.
  • Spread may be
    1. Via the lympahtics.
      • To the lymph nodes, lung and liver.
    2. Transcoelomic spread
      • Small, white plaques on serosa and adjacent tissues e.g. diaphragm.