JPC Systemic Pathology
SIGNALMENT (JPC #2287112): Slide A, adult cow
HISTORY: On routine abattoir examination, meat inspectors found an enlarged, firm liver.
HISTOPATHOLOGIC DESCRIPTION: Liver: Replacing hepatic parenchyma and compressing remaining hepatic chords is a marked increase in the number of bile ducts (biliary hyperplasia), which often form islands or lobules, concentrically surrounded by abundant fibrous connective tissue, up to 50 um thick and populated by low to moderate numbers of eosinophils, lymphocytes, macrophages, fewer plasma cells, and small amounts of hemorrhage and basophilic granular material (mineral). Focally an ectatic duct contains a section of a 0.25 mm wide adult trematode with a thin outer tegument overlying a band of somatic musculature, a parenchymatous matrix, and a uterus with numerous, asymmetrical, dark-brown, 100 x 40 um, singly operculated, thick-shelled eggs containing miracidia. In less affected parenchyma, multifocally expanding portal and centrilobular zones are dense collagen and reactive fibroblasts that often connect adjacent portal areas (bridging fibrosis), admixed with proliferating biliary epithelium forming small bile ducts (biliary ductular reaction) and previously described inflammatory cells, hemorrhage and mineralization. Adjacent to bands of fibrosis, there are few individualized hepatocytes that are shrunken with decreased cytoplasm (atrophy).
MORPHOLOGIC DIAGNOSIS: Liver: Cholangiohepatitis, fibrosing, lymphoplasmacytic and eosinophilic, chronic, multifocal, moderate, with cholangiectasia, marked biliary hyperplasia, bridging portal fibrosis and intraductal adult trematodes, breed unspecified, bovine
ETIOLOGIC DIAGNOSIS: Hepatic dicrocoeliasis
CAUSE: Dicrocoelium dendriticum
SYNONYMS: Lancet fluke disease; old world fluke disease
SIGNALMENT (JPC #3104055EV-UFMG 258-08): Slide B, Adult female intact domestic shorthair cat
HISTOPATHOLOGIC DESCRIPTION: Liver: Expanding portal areas and compressing adjacent sinusoids and hepatic cords are ectactic bile ducts with hyperplastic epithelium which often forms small papillary projections (biliary hyperplasia), surrounded by abundant fibrous connective tissue up to 50 um thick, which replaces hepatic parenchyma, and is populated with eosinophils, lymphocytes, macrophages, fewer plasma cells and contains small amounts of hemorrhage. Focally a duct contains a section of a 0.25 mm wide adult trematode with a thin outer tegument overlying a band of somatic musculature, a parenchymatous matrix, and a uterus with numerous, asymmetrical, yellow-brown, 100 x 40 um, singly operculated, thick-shelled eggs containing miracidia. Within the fibrous connective tissue surrounding ectatic bile ducts are increased numbers of bile ductules (biliary hyperplasia). In less affected parenchyma, multifocally expanding portal and centrilobular areas is fibrous connective tissue that often connects adjacent portal areas (bridging fibrosis), admixed with increased numbers of small bile ducts (biliary ductular reaction) and previously described inflammatory cells, hemorrhage and mineralization.
MORPHOLOGIC DIAGNOSIS: 1. Liver: Cholangiohepatitis, lymphoplasmacytic, and eosinophilic, multifocal, moderate with cholangiectasia, biliary hyperplasia, bridging portal fibrosis and intraductal adult trematodes, domestic shorthair, feline.
CAUSE: Platynosomum fastosum
SYNONYMS: Lizard poisoning
- Distributed worldwide with economic losses due primarily to condemnation of livers in the cattle industry
- Both Platynosomum fastosum and Dicrocoelium dendriticum: Class Trematoda, Order Plagiorchiida, Family Dicroceoliidae
- Small, narrow flukes, 0.5-1.0cm long
- Platynosomum fastosum: inhabit biliary ducts and gallbladder of cats
- Possible link to cholangiocarcinoma development
- Dicrocoelium dendriticum: bile duct parasite of sheep, cattle, pigs, deer, alpacas, woodchucks, cottontail rabbits
- Inhabits the gallbladder and bile and pancreatic ducts
- Infects cats, sheep, goats, cattle, new world camelids, buffalo, camels, rabbits, horses, and dogs
- Cats acquire by eating second intermediate or paratenic host (commonly lizards)
- A chronic, heavy parasite burden leads to biliary ectasia, and chronic cholangitis secondary to obstruction
- Indirect; two intermediate hosts required
- Platynosomum fastosum
- First intermediate host: Sublima octona snail
- Second intermediate host: Anolis Lizards, marine toads, geckos, various arthropods
- Cat becomes infected by ingesting second intermediate hosts à cercariae enter the upper digestive tract à cercariae migrate up the biliary tree à adults form in 8-13 weeks
- Dicrocoelium dendriticum
- First intermediate host: snail à cercariae expelled as “slime balls” from the snail’s lung during damp weather
- Second intermediate host: ant Forma fusca eat the “slime ball”
- Grazing animals ingest infected ants
- Metacercaria excyst in the small intestine and migrate up the bile duct into its fine ramifications and into the gallbladder
- Total life cycle takes 6 months
- The prepatent period for the definitive host is 7-9 days
TYPICAL CLINICAL FINDINGS:
- Usually none; often subclinical
- Severe infections (non-specific): anorexia, vomiting, lethargy, jaundice, death
- Anemia, emaciation, decreased lactation and lowered wool production (in sheep)
TYPICAL GROSS FINDINGS:
- 5-1.0cm long and 1mm wide, lancet-shaped and pied (blotchy because of brown uterus and white vitellaria visible through semitransparent tegument)
- Bile ducts: intraluminal flukes with bile duct wall thickening
- Early lesions:superficial erosions or visible scarring with sclerotic areas
- Chronic: extensive biliary fibrosis; liver margins are shrunken and sclerotic
TYPICAL LIGHT MICROSCOPIC FINDINGS:
- Trematodes are characterized by a an outer tegument, which may or may not have spines; a digestive tract consisting of paired blind ceca; a spongy parenchyma (acoelomate); vitellaria (yolk forming glands); and one or two prominent suckers; trematodes are monoecious (hermaphroditic- contain both male and female reproductive organs)
- Variable chronic cholangitis, fibrosing cholangiohepatitis, cholecystitis
- Bile ducts: dilation, epithelial hyperplasia, bridging portal fibrosis, mucous gland hyperplasia within large ducts
- Flukes and their eggs within the bile ducts with mucous exudate and cellular debris
ADDITIONAL DIAGNOSTIC TESTS:
- Oval brown operculate eggs 36-48um in diameter containing a miracidium; demonstrable in the feces using high density flotation solution (ZnSO4)
For Gross Lesions:
- Fasciola hepatica (common liver fluke of sheep and cattle): within bile ducts and gall bladder
- Young flukes are found in the bile ducts but can become encysted within the liver
- Mature flukes in large bile ducts results in cholangitis
- Fasciola gigantica: within bile ducts and gall bladder; 2-3x larger than hepatica
- Fascioloides magna: “large liver fluke of North America”; size - 80um × 300um fluke ound within liver parenchyma and often see black pigment deposits associated with migration in liver; less severe disease in tolerant wild ruminants than in domestic ruminants such as sheep
- Eurytrema pancreaticum and coelomatium: Mostly in pancreas, but can be in bile ducts in heavy burdens
Parasites of the pancreatic duct
- Dicrocoelium sp. infestations in new world camelids, hepatic fibrosis biliary hyperplasia and associated with pulmonary arterial lesions
- Dicrocoelium hospes (mostly sheep and cattle, but can infect other species) is prevalent in tropical regions; resembles D. dendriticum infection
- Dicrocoelium supperei is found in Austrian mouflons and roe deer
- Flukes of Opisthorchis family (Opisthorchis tenuicolis, Opisthorchis viverrini, Clonorchis sinensis, Metorchis albidis, Metorchis conjunctus)
- Flukes of Dicroceliidae family [Eurytrema pancreaticum, Concinnum (Eurytrema) procyonis, Dirocoelium dendriticum]
- Nematodes (ascarids) and cestodes can aberrantly migrate into pancreatic duct
- Platynosomum concinnum: Liver fluke of cats
- Bowman DD. In: Bowman DD, ed. Georgis’ Parasitology for Veterinarians. 10th ed. St. Louis, MO: Saunders Elsevier; 2013:3,133-134.
- Brown DL, Van Wettere AJV, Cullen JM. Hepatobiliary system and exocrine pancreas. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017:446-447.
- 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. St. Louis, MO: Elsevier Ltd; 2016:320-324.
- Hamir AN, Smith BB. Severe biliary hyperplasia associated with liver fluke infection in an adult alpaca. Vet Pathol. 2002;39(5):592–594.
- Hilbe M, Robert N, Pospischil A, Gerspach C. Pulmonary arterial lesions in new world camelids in association with Dicrocoelium dendriticum and Fasciola hepatica Vet Pathol. 2015;52(6):1202-1209.
- Pinto HA, Mati VLT, deMelo AL. New insights into the life cycle of Platynosomum (Trematoda: Dicrocoeliidae). Parasitol Res. 2014;113:2701–2707.