Upper Alimentary Tract Carcinoma Complex

Aetiology

• The most important oesophageal neoplasm is squamous cell carcinoma in the cow.
• This tumour is seen as part of a more general syndrome of upper alimentary tract neoplasia in adult cattle grazing rough pasture on which the bracken fern (Pteridium aquilinum) is present.
• The syndrome is seen in various part of the world including the Western Highlands of Scotland, Brazil and Kenya.
• In affected animals, squamous carcinomas may be present in the oropharynx, oesophagus and rumen and there may also be intestinal adenocarcinomas and bladder tumours, or the condition known as enzootic bovine haematuria.

Pathogenesis

• Experimentally, the feeding of bracken to laboratory animals will result in alimentary and bladder tumours.
• However, in many naturally-occurring cases of upper alimentary carcinoma in cattle there are coexisting viral papillomata, some of which show malignant change.
• The relationship between the ingestion of bracken and the presence of virus in the aetiology of the malignancies is currently the subject of intensive investigations.
• It may be that both are involved in the carcinogenesis.

Macroscopically

• These upper alimentary squamous carcinomas are most often seen as:
  • large
  • fungating
  • often superficially-necrotic
  • protruding into the lumen of the alimentary tract;
• There is often a marked scirrhous reaction.
• The tumours are locally aggressive and may permeate local lymphatics and metastasise to local lymph nodes.

Microscopically

The tumour consists of cords or groups of squamous cells, which may form keratin. Individual or multiple papillomata may be found in association with the carcinomata.

• The presence of the tumours interferes with normal alimentary function
  • there may be difficulty in chewing and swallowing or in cudding and eructation.