FINAL   DIAGNOSIS - Hepatic lipidosis Pancreatitis

History:  A 12-year-old female domestic shorthaired cat was submitted for complete necropsy.  The cat had been diagnosed with diabetes mellitus one month previously based on clinical pathology findings, but was not being treated with insulin.  The cat also had a reported history of recurrent urinary tract infections and vomiting for the previous two months.  Reported clinical pathology findings from shortly before the cat’s death revealed glucosuria and bilirubinuria as well as hypoalbuminemia, bilirubinemia, and elevated liver enzymes.  Physical examination as well as radiographs revealed ascites.

Gross Findings:  The carcass had abundant body fat stores and icterus was noted in multiple body tissues including the body fat, sclera, intima of great vessels, and skin.  The liver was diffusely yellow-tan with depressed, dark red foci, and floated in formalin.  The pancreas was pale, firm, and small.  The fat on either side of the pancreas had multiple white, chalky foci.  The abdomen was grossly distended with approximately 300 ml of serosanguinous fluid.

Histopathology:  Alterations included severe, diffuse hepatic vacuolar degeneration characterized by large clear vacuoles that displaced the nuclei to the periphery of cells.  The pancreatic acini were reduced in size and populated with cells devoid of zymogen granules.  There was fibrosis between lobules, sometimes extending into acini.  Several endocrine islets were expanded and replaced by a homogenous eosinophilic material that stained red with Congo red stain and had an apple-green birefringence under polarized light.  There were also locally extensive regions of peripancreatic fat necrosis.

Discussion:  The histopathologic lesions were consistent with pancreatitis and hepatic lipidosis.  The pancreatitis probably represented a chronic condition in which repeated episodes of mild to moderate pancreatic inflammation resulted in progressive loss or atrophy of pancreatic parenchyma and replacement by fibrous tissue.  The amyloid deposition in the pancreatic islets (detected with Congo red stain) is a common lesion in cats with diabetes mellitus.  Pancreatitis in cats has been associated with ileus and increased capillary permeability due to vascular injury with resultant abdominal effusion.

  Chronic relapsing pancreatitis with progressive loss of both exocrine and endocrine cells, followed by replacement with fibrous connective tissue, is a frequent cause of diabetes mellitus, especially in dogs.  Selective destruction of islet cells by infiltration of islets with amyloid is a common cause of diabetes mellitus in cats.  Elements of both processes were present in this case.  Diabetes mellitus is often, in turn, involved in the pathogenesis of hepatic lipidosis.  Hepatic lipidosis is a manifestation of abnormal metabolism in which the accumulation of lipids in the liver of a diabetic animal can result from increased fat mobilization and decreased utilization of lipids by injured hepatocytes.

-by Dr. Theresa Boulineau, ADDL Graduate Student