Primary Liver Tumours

Hepatocytic

  • more in dogs and cats
Gross
  • can be difficult to distinguish grossly from adenomas
  • usually one single large mass and additional smaller masses (intrahepatic metastases)
  • may have features of malignancy such as internal necrosis and haemorrhage
Microscopically
  • can be very variable appearing as sheets or cords of neoplastic cells
  • cells generally smaller with a higher nucleus to cytoplasmic ratio

Cholangiocellular - bile duct

  • more common than adenoma
  • reported in all species (mostly dogs and cats)
Gross
  • usually multiple whitish umbilicated nodules that are present diffusely throughout the liver
    • actually look as though they were secondary tumours
  • firm on cut surface
    • due to fibrosis
Microscopically
  • distinctly adenocarcinomatous
  • ductal and acinar proliferation in abundant fibrous tissue
  • sometimes papillary formations

Secondary Liver Tumours

  • from a variety of origins

Pancreatic

Pancreatic carcinoma (Image sourced from Bristol Biomed Image Archive with permission)

Image of haemorrhage and pancreatic carcinoma in a cat from Cornell Veterinary Medicine

  • In older dogs, more common in Airedale terriers, rare in cats, other species too
  • Tend to arise centrally in the gland
  • Highly invasive and infiltrative
  • Metastases to the liver, visceral serosa, abdominal lymph nodes, spleen, adrenals etc.
  • Similar to malignant ovarian tumours - implant on the peritoneum

Gross appearance

Pancreatic carcinoma (Image sourced from Bristol Biomed Image Archive with permission)
  • Usually spherical nodules with adhesions to nearby structures
  • Single or multiple, variable size
  • Greyish or yellow fibrous tissue - firm on cutting
  • May show internal necrosis and haemorrhage
  • Some tumours may contain cysts wih mucinous content
  • Adhesions may occur

Microscopic appearance

  • May be well differentiated with normal acini and ducts
  • Or diffuse sheet of undifferentiated cells

Endocrine Pancreatic

  • Larger than adenomas
  • Multilobular
  • Invasive into parenchyma and surrounding tissue
  • Metastasis into lymph nodes, liver mesentery, omentum
  • Few mitotic figures