Fat Necrosis, Abdominal

Abdominal fat necrosis

Pancreatic necrosis

Image of fat necrosis in a dog from Cornell Veterinary medicine

• Enzymatic necrosis of fat tissue
• Common sign of acute pancretic necrosis
• Limited to peripancreatic fat or thouout the abdomen
• Free droplets of fat found in peritoneal fluid
• Microscopic appearance
  • Acute lesion
    • Necrotic fat cells containing acidophilic, opaque, amorphous or lacy substance or granular material
    • Degenerate neutrophils
    • Necrotic debri
  • Chronic lesion
    • Fibroplasia
    • Vacuolated macrophages
    • Necrotic fat

Focal necrosis of abdominal fat

• Often in sheep, sometimes other species
• Small, dry, gritty plaques
• Microscopically resembles lesions in "pancreatic necrosis" above
• Possibly due to avascular necrosis
• Most common in very fat animals

Diffuse lipogranulomatosis

• Also called lipomatosis as sometimes found in abnormal locations
• Massive fat necrosis in cattle, mostly Channel Island breeds
• In excessively fat cattle
• Can be fatal or incidental finding
• May cause obstruction - intestinal, pelvic canal

• Clinical signs
  • Anorexia
  • Constipation
  • Diarrhoea
  • Colic
  • Bloat
  • Emaciation

• Gross appearance
  • Fat necrosis in omentum, mesentery, retroperitoneum, sometimes in intermuscular and subcutaneous fat
  • Masses vary in size, are encapsulated, surrounded by hyperaemia

• Microscopic appearance
  • Mixture of acute and chronic fat necrosis
  • Few neutrophils, lymphocytes, plasma ells
  • Many macrophages, giant cells
  • Interstitial fibrosis

• Causes are uncertain
  • Dietary cause
  • Chemical composition of fat
    • Ruminal production of high levels of saturated fatty acids that become solid at body temperature, lipases from damaged fat cells produce crystalline material which causes inflammatory reaction ending with accumulation of foreign material and fibrosis