Histology and immunohistochemistry of severe inflammatory bowel disease versus lymphoma in the ferret (Mustela putorius furo).

Inflammatory bowel disease (IBD) is a common disorder of ferrets (Mustela putorius furo) that may progress to lymphoma. Although routine histology is used to distinguish between these diseases, misclassifications may occur. Immunohistochemistry (IHC) is commonly used to distinguish between IBD and lymphoma in small animals. The objective of our study was to determine the agreement in the diagnosis reached solely using hematoxylin and eosin (HE)-stained, full-thickness sections versus using a combination of HE and IHC. Enteric sections from 44 ferrets previously diagnosed with IBD or intestinal lymphoma and 3 control ferrets were analyzed by pathologists with expertise in ferrets. A pathologist blinded to the original diagnosis assessed the same HE-stained sections. Analysis was then repeated using HE sections in parallel with sections stained using antibodies against CD3 and CD79a. No significant difference was found between the original HE diagnosis and the HE diagnosis reached by the blinded pathologist (p = 0.91) or between the blinded pathologist's HE versus HE with IHC diagnosis (p = 0.16). In the 2 cases where disagreement was present, IHC was pivotal in reaching a final diagnosis. There was no significant age (p = 0.29) difference between diagnoses; however, significantly more male ferrets were affected with IBD than females (p = 0.004). Immunophenotype of the lymphoma was not correlated with predilection for location in the intestinal wall (p = 0.44). Results suggest that although IHC is not necessary to distinguish IBD from intestinal lymphoma in ferrets, it can be useful a definitive diagnosis in cases of severe IBD.