Intrahepatic Cholangiocarcinoma Identified in a Zoo-Housed Sandhill Crane (Grus canadensis): An Anatomopathological and Metagenomic Study

SIMPLE SUMMARY: A male sandhill crane (Grus canadensis) was imported from the Netherlands in 2013 and bred for 8 years in a zoo for a crane-species restoration project in Gangwon Province in South Korea. The adult bird showed no clinical symptoms before its death. This study describes the anatomopathological finding of intrahepatic cholangiocarcinoma diagnosed in the captive sandhill crane, and metagenomic sequencing was performed to elucidate the etiology. This is the first report where the gross and histological characteristics of intrahepatic cholangiocarcinoma in a sandhill crane are described. No viral cause was identified in the metagenomics analysis and PCR of the cholangiocarcinoma sample, but a contributing role of Cutibacterium sp. and E. coli identified from the metagenomics could not be excluded. ABSTRACT: Tumors in birds can be caused by a variety of factors such as species, age, sex, virus, chemicals, and environment. In particular, tumors are a major cause of death in long-lived birds such as parrots and zoo birds. A male sandhill crane that was bred for 8 years in a zoo was diagnosed with intrahepatic cholangiocarcinoma (ICC). At necropsy, the liver revealed a multinodular mass of variable colors, and severe cirrhosis and hemorrhages were present. Histologically, ICC was characterized by the presence of both types of ICC: small-duct type and large-duct type. Large-duct-type ICC was distinguished by the presence of multifocal biliary neoplasia, characterized by the diffuse papillary proliferation of columnar cells resembling large cholangiocytes. Small-duct-type ICC was characterized by the presence of non-mucin-producing cuboidal cells such as bile duct cells. In this case, no viral cause was identified from the metagenomic analysis and PCR of ICC; however, a contributing role of Cutibacterium sp. and E. coli identified from the metagenomics could not be excluded. This study is the first to describe the anatomopathological characteristics of ICC in the studied sandhill crane and attempts to determine its potential infectious etiology using metagenomics.