JPC SYSTEMIC PATHOLOGY
DIGESTIVE SYSTEM
October 2018
D-T13 (NP)

Signalment (JPC# 1851823):  Eight-month-old castrated male polypay-cross lamb

HISTORY:  This lamb died during an outbreak of severe photosensitization.

HISTOPATHOLOGIC DESCRIPTION:  Liver:  Diffusely, portal areas are expanded by abundant fibrosis that extends between portal areas (portal bridging fibrosis), frequently surrounds, separates and individualizes lobules of hepatocytes and contains numerous embedded variably-sized bile duct profiles (biliary ductular reaction) admixed with few lymphocytes, plasma cells and neutrophils.  Multifocally bile canaliculi are expanded by variably-sized accumulations of green-brown bile pigment (cholestasis). Hepatocytes in these areas of cholestasis and adjacent to fibrotic portal areas are often degenerate, characterized by swollen hepatocytes with pale vacuolated cytoplasm, or necrotic, characterized by shrunken, hypereosinophilic cytoplasm with nuclear pyknosis, karyorrhexis or karyolysis.  There is also occasional loss of hepatic cord architecture with replacement by eosinophilic cellular and karyorrhectic debris, few neutrophils, macrophages, lymphocytes, and plasma cells (lytic necrosis).

MORPHOLOGIC DIAGNOSIS:  Liver:  Fibrosis, portal and bridging, diffuse, moderate, with biliary ductular reaction, cholestasis, hepatocellular degeneration and necrosis, and minimal lymphoplasmacytic cholangiohepatitis, polypay-cross, ovine.

ETIOLOGIC DIAGNOSIS:  Mycotoxic hepatic fibrosis

CAUSE:  Sporidesmin intoxication

CONDITION:  Facial eczema

GENERAL DISCUSSION:

PATHOGENESIS:

TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS: 

TYPICAL LIGHT MICROSCOPIC FINDINGS:

DIFFERENTIAL DIAGNOSIS:

References:

  1. Brown DL, Van Wettere AJ, Cullen JM. Hepatobiliary system and exocrine pancreas. In: Zachary JF, McGavin MD, eds. Pathologic Basis of Veterinary Disease. 6th St. Louis MO: Elsevier; 2017:430, 450-451.
  2. Collett MG. Bile duct lesions associated with turnip (Brassica rapa) photosensitization compared with those due to sporidesmin toxicosis in dairy cows. Vet Pathol. 2014;51(5):986-991.
  3. Cullen JM, Stalker MJ. Liver and biliary system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 2. 6th ed. Louis, MO: Elsevier; 2016:335-336.
  4. Hansen DE, McCoy RD, Hedstrom OR, Snyder SP, Ballerstedt PB. Photosensitization associated with exposure to Pithomyces chartarum in lambs. J Am Vet Med Assoc. 1994;204:1668-1671.
  5. Radostits OM, Gay CC, Blood DC, Hinchcliff KW. Veterinary Medicine, A Textbook of the Diseases of Cattle, Sheep, Pigs, Goats and Horses. 11th ed. Louis, MO: Elsevier; 2017:652-654.


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