SYSTEMIC PATHOLOGY

DIGESTIVE SYSTEM

October 2024

D-N09 (NP)

 

Signalment (JPC# 2547361): 6-year-old male military macaw (Ara militaris) 

 

HISTORY: Behavior and appetite were normal at time of death. The macaw was exposed to a conure that died with nonspecific signs.

 

HISTOPATHOLOGIC DESCRIPTION: 

Liver: Effacing >90 of the hepatic parenchyma and separating, surrounding, and infiltrating remaining islands of normal hepatocytes is an unencapsulated, infiltrative, moderately cellular neoplasm composed of polygonal cells arranged in irregular, branching, and anastomosing tubules and acini on a moderate fibrovascular and multifocally desmoplastic stroma. Neoplastic cells have variably distinct cell borders, a moderate amount of pale eosinophilic and vacuolated cytoplasm, and a round to oval nucleus with finely-stippled chromatin and 1-2 distinct nucleoli. The mitotic count is 1 per 2.37mm², and there is occasional single cell necrosis within the neoplastic cells. Multifocally, remaining hepatocytes are occasionally swollen with lacy, microvacuolated cytoplasm (glycogen change) or shrunken with brightly eosinophilic cytoplasm and a pyknotic nucleus (necrosis). There are low numbers of lymphocytes and plasma cells scattered through the hepatic parenchyma. 

 

Mucosa, oropharynx (per contributor): Extending from a thin fibrovascular stalk is an exophytic neoplasm composed of polygonal cells undergoing squamous differentiation arranged in anastomosing trabeculae that form papillary frond-like projections supported by a highly vascular fibrous stalk. Neoplastic cells have variably distinct cell borders, a moderate amount of eosinophilic cytoplasm, and a round to oval nucleus with finely stippled chromatin and a single prominent nucleolus. The mitotic count is 1 per 2.37mm². Multifocally, there is parakeratotic hyperkeratosis and epidermal erosions. Multifocally, there are moderate numbers of heterophils that transmigrate the epidermis and moderate numbers of lymphocytes and plasma cells within the dermis.

 

MORPHOLOGIC DIAGNOSIS: 

1. Liver: Cholangiocarcinoma, military macaw (Ara militaris), avian.
2. Mucosa, oropharynx (per contributor): Papilloma.

 

SYNONYMS: Bile duct carcinoma, cholangiocellular carcinoma

 

GENERAL DISCUSSION:

• Cholangiocarcinoma
  1. Adenocarcinoma arising from a bile duct; can be intrahepatic, hilar, or extrahepatic
     • Extrahepatic (of the gallbladder or extrahepatic biliary ducts) are much less frequent than intrahepatic
  2. Invasive and aggressive
     • Spreads along the biliary tract to the capsule
     • Metastasizes to abdominal lymph nodes, mesentery, viscera, and lungs
     • Papillomatosis is the most common neoplasm of the oral cavity and cloaca in New World psittacines
       1. Psittacid herpesvirus (PsHV) genotypes 1, 2, and 3 have been linked to mucosal papillomas in New World parrots
       2. Hyperplastic and neoplastic changes of bile and/or pancreatic ducts occur within increased frequency in birds with mucosal papillomas
       3. Oral papillomas tend to occur at the base of tongue, margins of the choana, and glottis
       4. Oral and cloacal papillomas are more common than those in the esophagus, proventriculus, and ventriculus

 

PATHOGENESIS:

• Cholangiocarcinoma: May be associated with chronic fluke infestations
  1. Platynosomum fastosum, found in the biliary ducts and gallbladder of infected cats, results in fibrosing cholangiohepatitis, and cholecystitis, with dilated and hyperplastic ducts, and has been found in some cats with cholangiocarcinoma
• Papilloma
  1. PsHV 1, 2, and 3 has been associated with internal papillomatosis and hyperplastic and neoplastic bile duct and pancreatic duct lesions in New World psitticines (particularly macaws and Amazon parrots) which can occur concurrently
  2. Papillomaviruses have been associated with squamous papillomas in Amazon parrots, but are not associated with mucosal papillomas in Amazon parrots and macaws
  3. See systemic I-V01 for further discussion of viral papillomas

 

TYPICAL CLINICAL FINDINGS:

• Cholangiocarcinoma: Emaciation, weakness, hepatomegaly, ataxia, trembling, seizures (due to hepatic encephalopathy); peritoneal/abdominal effusion; sudden death
• Mucosal/alimentary papillomas: Mucosal discoloration, blunting, dyschezia, vent staining, infertility (mechanical obstruction and interference with breeding), hematochezia
• Cutaneous papilloma: Slow growing, wart-like proliferations on non-feathered skin (feet, legs, face, eyelids, wing, and beak commissure)
• Cloacal papilloma: Cloacal prolapse, dyschezia, tenesmus, hematochezia, flatulence, cloacoliths, infertility

 

TYPICAL GROSS FINDINGS:

• Cholangiocarcinoma: 
  1. Multiple firm, pale beige masses with a typical central umbilicated appearance; may be diffuse
  2. Multiple nodules due to possible intrahepatic metastases or multicentric origin
• Papilloma:
  1. Pink to white, fleshy or cobblestone-like growths 
  2. May be smooth and pale in the oral cavity and esophagus
  3. Single large masses or many small masses
  4. Friable; bleed or bruise easily; may be ulcerated

 

TYPICAL LIGHT MICROSCOPIC FINDINGS:

• Cholangiocarcinoma
  1. Ductules, acini, and occasionally papillary projections of columnar to cuboidal cells 
  2. May have a mix of well-differentiated acini that contain mucins (not bile) admixed with poorly differentiated areas
  3. Abundant mitotic figures
  4. May induce a marked scirrhous reaction (desmosplasia)
  5. Highly invasive growth pattern
  6. Difficult to distinguish from metastatic adenocarcinomas
• Papilloma
  1. Papillary mass with pedunculated fibrovascular connective tissue stalk
  2. Heavily keratinized stratified squamous epithelium
  3. May see intranuclear herpesviral inclusion bodies at junction of keratinized and non-keratinized epithelium
  4. In gastrointestinal tract, may contain mucous glands
  5. Inflammatory cells in the stroma

 

ADDITIONAL DIAGNOSTIC TESTS:

• Immunohistochemistry
  1. Cholangiocellular tumors are immunoreactive to pancytokeratin (AE1/AE3), including cytokeratin 7 (found in biliary epithelium) (Cullen, 2016) and cytokeratins 14 and 19 and are negative for hepatocyte paraffin 1 (Hep-Par1) (Tsuji, Vet Pathol., 2019) (Barrantes Murrillo, J Vet Diagn Invest., 2024)

 

DIFFERENTIAL DIAGNOSIS:

• Cholangiocarcinoma
  1. Primary intrahepatic cholangiocellular carcinoma can be difficult to impossible to distinguish from metastatic adenocarcinomas, especially pancreatic or mammary adenocarcinomas
  2. Cholangioma: Uncommon, a benign, usually solitary neoplasm
  3. Bile duct hyperplasia associated with hepatic lipidosis or portal fibrosis
  4. Bile duct proliferation induced by chronic hepatotoxins (e.g., aflatoxicosis)
  5. Hepatocellular tumor
     • Can usually be distinguished from hepatocellular neoplasia by multiplicity, firmness, pale beige color (increased stroma), and umbilicate appearance of those involving the capsule; hepatocellullar carcinomas are immunoreactive for: Alpha-fetoprotein; HepPar-1
  6. Pancreatic duct adenoma/adenocarcinoma (if invaded into the liver)
  7. Mixed hepatocellular and cholangiocellular carcinoma: Rare; IHCs as described above can confirm hepatocytic nature
• Papilloma
  1. Nodular forms of avian pox, characterized by epithelial ballooning degeneration and presence of Bollinger bodies (large, lipophilic intracytoplasmic viral inclusion bodies)
  2. Cutaneous/squamous papillomas in multiple avian species are linked to avian papilloma viruses
  3. Squamous cell carcinoma 

 

COMPARATIVE PATHOLOGY:

• Cholangiocarcinoma: 
  1. Cholangiocarcinoma has been noted in many species, including dogs, cats, sheep, cattle, horses, and goats; as well as mice, prosimians, NHPs llamas, fruit bats, bearded dragons, and cartilaginous fish (Chondrichthyes); it is relatively common in fennec foxes and polar bears
  2. Cats
     • Feline paraneoplastic alopecia, as well as skin fragility syndrome has been associated with pancreatic carcinoma, neuroendocrine pancreatic neoplasia, cholangiocarcinoma, hepatocellular carcinoma, hepatosplenic plasma cell tumor, and metastatic intestinal carcinoma 
  3. Bovine
     • Report of metastatic hepatic cholangiocarcinoma with metastases effacing hepatic parenchyma, omentum, mesentery, ruminal serosa, and diaphragm that strikingly mimicked tuberculosis (Mycobacterium PCR negative) (Elbert, J Vet Diagn Invest. 2021)
  4. Horse
     • Intrahepatic mucinous cholangiocarcinoma reported in a horse with mild recurrant colic; neoplasltic cells were arranged in cells were arranged in large cysts containing lakes of mucin comprising 90% of the tumor volume
  5. Vervet monkey: Report of a cholangiocarcinoma with unique immunohistochemical staining (positive for tumor cell cycle regulator 4-3-3-σ and E-Cadherin) (Suárez-Bonnet, J Comp Pathol. 2020)
  6. Sugar glider: Cholangiocarcinoma with carcinomatosis reported in a sugar glider with abdominal effusion and multiple adhesions (Williams, J Vet Diagn Invest. 2024)
  7. Fruit bats Hepatocellular carcinoma and cholangiocarcinoma is to be associated with liver damage from iron overload
• Papilloma:
  1. Reported in most domestic species
  2. Bovine alimentary papillomatosis is caused by bovine papillomavirus 4 (BPV-4)
  3. Papillomaviruses have also been associated with sarcoids in horses and cats and squamous cell carcinoma in multiple species
  4. Avians: A recent study on avians papilloma and squamous cell carcinoma showed that SCC have significantly higher nuclear pleomorphism and are more commonly ulcerated than are papillomas; SCCs also demonstrate higher COX-2 total score and lack of E-cadherin; all papillomas and SCCs tested were negative for Psittacus erithacus papillomavirus 1 and Psittacid herpesvirus 1 (Jones, J Comp Pathol., 2020)

 

REFERENCES:

1. Abdul-Aziz T, Fletcher OJ. Chapter 8: Hepatobiliary System. In: Abdul-Aziz T, Fletcher OJ, Barns HJ, eds. Avian Histopathology. 4th ed. Madison, WI: Omnipress; 2016: 419-420.
2. Abdul-Aziz T, Fletcher OJ. Chapter 12: Endocrine System. In: Abdul-Aziz T, Fletcher OJ, Barns HJ, eds. Avian Histopathology. 4th ed. Madison, WI: Omnipress; 2016: 547.
3. Barthold SW, Griffey SM, Percy DH. Mouse. In: Pathology of Laboratory Rodents and Mouse. 4th ed. Ames, IA: Wiley Blackwell; 2016:113-114.
4. Boes KM. Chapter 6: Body Cavity Fluids. In: Raskin RE, Meyer DJ, & Boes KM eds. Canine and Feline Cytopathology: A Color Atlas and Interpretation Guide. 4th ed. St. Louis, MO: Elsevier; 2022:271.
5. Barrantes Murillo DF, Cattley RC, et al. Intrahepatic mucinous cholangiocarcinoma with recurrent colic in a horse case report and literature review of cholangiocarcinoma in horses. J Vet Diagn Invest. 2024;36(4):547-553.
6. 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; 2016:322, 348-349.
7. Elbert JA, Sanchez S, Rissi DR. Metastatic cholangiocarcinoma mimicking tuberculosis in a cow. J Vet Diagn Invest. 2021;33(6):1180-1182.Fletcher OJ, Abdul-Aziz T. Chapter 6: Respiratory System. In: Abdul-Aziz T, Fletcher OJ, Barns HJ, eds. Avian Histopathology. 4th ed. Madison, WI: Omnipress; 2016: 276. 
8. Farina LL, Lankton JS. Chiroptera. In: Terio KA, McAloose D, St. Leger J, eds. Pathology of Wildlife and Zoo Animals. London, UK: Academic Press; 2018:610, 615. 
9. Jones AL, Suárez-Bonnet A, Mitchell JA, Ramirez GA, Stidworthy MF, Priestnall SL. Avian Papilloma and Squamous Cell Carcinoma: a Histopathological, Immunohistochemical and Virological study. J Comp Pathol. 2020;175:13-23.
10. Keel MK, Terio KA, McAloose D. Canidae, Ursidae, and Ailuridae. In: Terio KA, McAloose D, St. Leger J, eds. Pathology of Wildlife and Zoo Animals. London, UK: Academic Press; 2018:236-238. 
11. McAloose D, Stalis IH. Prosimians. In: Terio KA, McAloose D, St. Leger J, eds. Pathology of Wildlife and Zoo Animals. London, UK: Academic Press; 2018:339.e8. 
12. Mauldin EA, Peters-Kennedy J. Integumentary System. In: Maxie MG, ed. Jubb, Kennedy & Palmer's Pathology of Domestic Animals. Vol 1. 6th ed. St. Louis, MO: Elsevier; 2016:545, 712.
13. Origgi FC. Lacertilia. In: Terio KA, McAloose D, St. Leger J, eds. Pathology of Wildlife and Zoo Animals. London, UK: Academic Press; 2018:889.e7. 
14. Reavill DR, Dorrestein G. Psittacines, Coliiformes, Musophagiformes, Cuculiformes. In: Terio KA, McAloose D, St. Leger J, eds. Pathology of Wildlife and Zoo Animals. London, UK: Academic Press; 2018:782-783, 788. 
15. Schmidt R, Reavill DR, Phalen DN. Liver. In: Pathology of Pet and Aviary Birds. 2nd ed. Ames, IA: John Wiley & Sons, Inc.; 2015:119.
16. Shivaprasad HL, Barnes HJ. Chapter 14: Integumentary System. In: Abdul-Aziz T, Fletcher OJ, Barns HJ, eds. Avian Histopathology. 4th ed. Madison, WI: Omnipress; 2016: 619.
17. Spagnoli ST, Gelberg HB. Alimentary System and the Peritoneum, Omentum, Mesentery, and Peritoneal Cavity. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 7th ed. St. Louis, MO: Elsevier; 2022:427, 432, 467, 469. 
18. Stedman NL, Garner MM. Chondrichthyes. In: Terio KA, McAloose D, St. Leger J, eds. Pathology of Wildlife and Zoo Animals. London, UK: Academic Press; 2018: 1016.e10. 
19. Stidworthy MF, Denk D. Sphenisciformes, Gaviiformes, Podicipediformes, Procellariiformes, and Pelecaniformes. In: Terio KA, McAloose D, St. Leger J, eds. Pathology of Wildlife and Zoo Animals. London, UK: Academic Press; 2018:664. 
20. Suárez-Bonnet A, Priestnall SL, Ramírez GA, Molín J, Jaber JR. Aberrant Expression of Cell Cycle Regulator 14-3-3-σ and E-Cadherin in a Metastatic Cholangiocarcinoma in a Vervet Monkey (Chlorocebus pygerythrus). J Comp Pathol. 2020;179:25-30.
21. Tsuji Y, Kuramochi M, et al. Hepatic Myoepithelial Carcinoma in a Dog: Immunohistochemical Comparison With Other Canine Hepatic Carcinomas. Vet Pathol. 2019;56(6):889-894. 
22. Uzal FA, Plattner BL, Hostetter JM. Alimentary System. In: Maxie MG, ed. Jubb, Kennedy & Palmer's Pathology of Domestic Animals. Vol 2. 6th ed. St. Louis, MO: Elsevier; 2016:22. 
23. Van Wettere AJ, Brown DL. Hepatobiliary System and Exocrine. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 7th ed. St. Louis, MO: Elsevier; 2022:545. 
24. Welle MM, Linder KE. The Integument. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 7th ed. St. Louis, MO: Elsevier; 2022:1261.
25. Williams AL, Brum Rosa F. Cholangiocarcinoma with carcinomatosis in a sugar glider. J Vet Diagn Invest. 2024;36(4):543-546.

Click the slide to view.

---