Adenoma

Oral Papilloma Neoplasia in Dog (Courtesy of Alun Williams (RVC))

• Adenomas are unusual but may develop in oropharyngeal salivary tissue.

Intestinal adenoma

Adenoma of brunners glands (duodenum) (Courtesy of Bristol BioMed Image Archive)

• An adenoma is a growth of glandular origin.
• Intestinal adenomas are found in both the small and large intestines.
• Intestinal adenomas usually grow into the lumen.
• These growths are bengin and polyp-like.

Tumours of the Perianal Area

Hepatoid Gland Tumours (Perianal Adenomas)

Perianal gland- normal (Courtesy of Bristol BioMed Image Archive)

* Affect the dog.

• Arise from the solid, modified sebaceous circumanal glands.
• Common in ageing entire males.
  

  Perianal gland- adenoma (Courtesy of Bristol BioMed Image Archive)

• Lesions range from hyperplasia to true adenomas (benign).
  • These low grade lesions are under hormonal control.
    • Castration/ administation of oestrogens or anti-androgens causes reduction in size.
      

      Perianal adenoma- gross appearance (Courtesy of Bristol BioMed Image Archive)
• Occasionally hepatoid carcinomas (malignant) arise in affected males
  • Outwith hormonal control.
• Hepatoid gland tumours occur rarely in bitches.
  • Are commonly malignant.
• Hepatoid glands are also found at the tail head, prepuce and occasionally other skin sites.
  • Hepatoid tumours can also arise in these areas.

Hepatocytic

• seen mostly in sheep and cattle

Gross

• a single, pale, soft, often large nodule
• well demarcated from adjacent tissue, often with a noticeable capsule

Microscopically

• normal hepatocytic appearance
• no portal tracts within the mass
• a capsule surrounds the growth

Cholangiocellular - bile duct

• very rare
• reported in dogs and cats

Pancreatic

Image of multifocal pancreatic adenoma in a dog from Cornell Veterinary Medicine

• Very rare
• May be difficult to distinguish from nodular hyperplasia
• Single and larger nodules than normal pancreas