Choledochal cyst with secondary cholangitis, choledochitis, duodenal papillitis, and pancreatitis in a young domestic shorthair cat

Choledochal cysts, congenital segmental dilations of the common bile duct, have been reported in few cats, and histologic characterization is lacking. A 20-mo-old spayed female domestic shorthair cat was presented because of vomiting and weight loss. There was progressive elevation of liver enzyme activity (ALT > ALP, GGT) and hyperbilirubinemia. Diagnostic imaging identified focal cystic dilation of the common bile duct, dilation and tortuosity of adjacent hepatic ducts, and a prominent duodenal papilla. A choledochal cyst was suspected, and the animal was euthanized. On postmortem examination, there was a 2-cm, firm, thickened, cystic dilation of the common bile duct, patent with adjacent ducts. Histologically, the cyst wall was expanded by fibroblasts, collagen, and lymphoplasmacytic inflammation. Adjacent bile ducts were markedly dilated and tortuous, with lymphoplasmacytic inflammation and papillary mucosal hyperplasia that extended to the major duodenal papilla. There was chronic neutrophilic cholangitis, suggesting bacterial infection and/or disturbed bile drainage, extrahepatic obstruction, and lymphoplasmacytic pancreatitis with ductular metaplasia. Prominent lymphoid follicles within biliary ducts and duodenum suggested chronic antigenic stimulation. Choledochal cysts can be associated with chronic neutrophilic cholangitis, extrahepatic obstruction, choledochitis, duodenal papillitis, and pancreatitis, and should be a differential for increased hepatic enzymes and hyperbilirubinemia in young cats.

Ductal Plate Malformations in Captive Snakes

Ductal plate malformations are abnormalities in the liver that arise from inappropriate or incomplete remodeling of the embryologic ductal plate. Various types of ductal plate malformations are reported in the human and veterinary literature, most commonly affecting domestic mammalian species but also fish. We investigated the occurrence and described the histopathologic features of ductal plate malformations in captive snakes. Malformations were identified in 18 snakes: 10 colubrids, 6 vipers, and 2 boids. There was no sex predilection, and the mean age was 17 years. The majority of lesions were incidental with most snakes having one or more comorbidities, most commonly neoplasia or systemic inflammation, that resulted in natural death or euthanasia. Ductal plate malformations in all livers were broadly characterized by a well-demarcated nodule of irregular bile ducts embedded within a varying amount of fibrous stroma. Malformations were further categorized based on the amount of fibrous stroma and dilation of the bile ducts as von Meyenburg complexes, cystic liver disease, and/or an intermediate hybrid subtype representative of cysts arising within von Meyenburg complexes. Histochemical and immunohistochemical staining, including Gomori's trichome and pan-cytokeratin, respectively, were applied on select cases to confirm histologic features. Malignant transformation was not identified within this population.

Caroli Syndrome in a 6-Year-Old Rottweiler Dog

A 6-year-old entire female rottweiler dog with a recent history of ascites and respiratory disease was submitted for necropsy examination. The dog had been diagnosed ultrasonographically with biliary cysts as a puppy. Grossly, the liver was smaller than expected with an irregular surface. Islands of hepatocytes were separated by bands of fibrosis and many bile ducts were markedly dilated. Histologically, extensive fibrosis extended beyond the limiting plate and into the surrounding hepatic parenchyma and was associated with abundant small bile ducts throughout. In conjunction with the detection of biliary cysts early in life, the gross and histological findings were consistent with a diagnosis of Caroli syndrome. In man, Caroli syndrome is frequently associated with renal and pancreatic cysts; a single renal cyst was identified in this case.

Congenital Hepatic Fibrosis in a Purebred Spanish Horse Foal: Pathology and Genetic Studies on PKHD1 Gene Mutations

A 1-month-old Purebred Spanish Horse (PSH) foal presented with progressive hepatic failure culminating in death. Hepatic lesions were consistent with congenital hepatic fibrosis (CHF). Genetic studies in the PKHD1 gene in the affected foal revealed that it was heterozygous for the 2 previously described single-nucleotide polymorphisms (SNPs) linked to CHF in Swiss Franches-Montagnes (SFM) horses. In addition, 2 novel mutations were detected, the foal being homozygous for one of them and heterozygous for the other. Genetic studies in a healthy PSH population ( n = 35) showed a 3-fold higher genotypic frequency for PKHD1 SNP g.49,630,834G>A and a 5-fold higher genotypic frequency for PKHD1 SNP g.49,597,760A>T compared with those reported for SFM horses. SNPs in the PKHD1 gene in CHF-affected SFM horses might not fully explain the CHF observed in the PSH. Other mutations in the PKHD1 gene could play a more important role in the PSH.

Congenital hepatic fibrosis and polycystic kidney disease not linked to C >A mutation in exon 29 of PKD1 in a Persian cat

CASE SUMMARY

We describe the case of a 1-year-old male Persian cat diagnosed with congenital hepatic fibrosis (CHF) associated with renal polycystic disease and, for the first time, we have shown that there was no C >A mutation in exon 29 of PKD1 (polycystic kidney disease 1). The cat presented with a history of chronic weight loss, anorexia, vomiting, depression and lethargy, with profuse salivation and ascites on clinical examination. A mild elevation in liver-associated plasma enzymes suggested a hepatic disease. Owing to the cat's deteriorating condition, it was euthanized. During necropsy, the liver was found to be enlarged, firm and reddish, and the kidney had multiple small cortical cysts. Immunohistochemistry revealed that bile duct cells and epithelial cells of renal cysts showed positive immunoreactivity to keratin 19. Collagen fibers surrounding bile ducts within portal areas demonstrated reactivity to type IV collagen antibody, confirming the congenital nature of the process. A diagnosis of ductal plate malformation consistent with CHF associated with polycystic kidney in a young Persian cat was made. Interestingly, genetic testing revealed a wild-type sequence at position 3284 in exon 29 of PKD1.

RELEVANCE AND NOVEL INFORMATION

The absence of the classic genetic mutation associated with the particular clinical presentation supports the hypothesis of a distinct etiopathogenesis among fibropolycystic diseases in domestic cats. Moreover, congenital hepatic fibrosis is a rare but important differential diagnosis for young Persian cats and their crosses with clinical signs of chronic end-stage liver disease.

Congenital hepatic fibrosis in the Franches-Montagnes horse is associated with the polycystic kidney and hepatic disease 1 (PKHD1) gene

Congenital hepatic fibrosis has been described as a lethal disease with monogenic autosomal recessive inheritance in the Swiss Franches-Montagnes horse breed. We performed a genome-wide association study with 5 cases and 12 controls and detected an association on chromosome 20. Subsequent homozygosity mapping defined a critical interval of 952 kb harboring 10 annotated genes and loci including the polycystic kidney and hepatic disease 1 (autosomal recessive) gene (PKHD1). PKHD1 represents an excellent functional candidate as variants in this gene were identified in human patients with autosomal recessive polycystic kidney and hepatic disease (ARPKD) as well as several mouse and rat mutants. Whereas most pathogenic PKHD1 variants lead to polycystic defects in kidney and liver, a small subset of the human ARPKD patients have only liver symptoms, similar to our horses with congenital hepatic fibrosis. The PKHD1 gene is one of the largest genes in the genome with multiple alternative transcripts that have not yet been fully characterized.

We sequenced the genomes of an affected foal and 46 control horses to establish a comprehensive list of variants in the critical interval. We identified two missense variants in the PKHD1 gene which were strongly, but not perfectly associated with congenital hepatic fibrosis. We speculate that reduced penetrance and/or potential epistatic interactions with hypothetical modifier genes may explain the imperfect association of the detected PKHD1 variants. Our data thus indicate that horses with congenital hepatic fibrosis represent an interesting large animal model for the liver-restricted subtype of human ARPKD.

Congenital hepatic fibrosis in 5 dogs

Congenital hepatic fibrosis is a disorder of biliary system development histologically characterized by diffuse periportal to bridging fibrosis with numerous small often-irregular bile ducts and reduction in the number of portal vein branches. The condition results from abnormal development of the ductal plate, the embryonic precursor to the interlobular bile ducts. It has rarely been reported in veterinary species, and it has never been reported in dogs. This article describes 5 cases of a ductal plate malformation in dogs consistent with congenital hepatic fibrosis. On light microscopy, all 5 livers had severe bridging fibrosis with a marked increase in the number of small bile ducts, which often had irregular, dilated profiles reminiscent of the developing ductal plate. In addition, 80% (4 of 5) of cases lacked typical portal vein profiles. Cytokeratin 7 and proliferating cell nuclear antigen immunohistochemistry was performed on the 3 cases for which paraffin-embedded tissue was available. The bile duct profiles were strongly positive for cytokeratin 7 in all 3 cases, and they were negative for proliferating cell nuclear antigen or only had rare positive cells. All 5 dogs presented with clinical signs of portal hypertension. Congenital hepatic fibrosis should be considered in the differential diagnosis in young dogs that present with portal hypertension and lesions that may have been interpreted as bridging biliary hyperplasia or extrahepatic biliary obstruction.