Kathy Mu¹, Gustavo Ramirez², Bernat Marti-Garcia¹, Jessica Molin², Deepa Cavalli-Sforza¹, Alejandro Suarez-Bonnet¹

¹The Royal Veterinary College, Hatfield, United Kingdom. ²Universitat de Lleida, Lleida, Spain

Objectives

To histopathologically characterize a cohort of formalin fixed paraffin embedded (FFPE) feline cholangiocarcinoma (CCA) tissue samples.

To investigate the expression of CD44 in normal, non-cancerous feline liver tissues to compare it with CCA cases.

To investigate potential statistically significant associations between the expression of CD44 in feline CCA and histopathological features of malignancy (cell proliferation-mitotic index, necrosis, cellular morphology, inflammation, invasiveness, histological subtype, vascular / lymphatic invasion, grading).

Methods

Twenty haematoxylin and eosin tissue sections from 20 feline CCA were immunohistochemically stained with a monoclonal antibody anti-CD44. Intensity and percentage of positive cells were used to produce a total score (TS) for each case, as well as for the histologically normal liver parenchyma present and adjacent to tumour areas, in each of the sections examined. TS was compared between normal liver parenchyma, CCA, and histopathological features.

Results

CD44 was significantly overexpressed in comparison to areas of histologically normal liver parenchyma (p < 0.001). Normal liver parenchyma showed weak and heterogeneous expression in cholangiocytes while neoplastic cells where strongly positive in the majority of cases. There was no statistical association between CD44 expression and histopathological features.

Statement: Impact/ Clinical Significance

To the authors' knowledge, this is the first study to demonstrate that an important therapeutic target (CD44) in human oncology is overexpressed in feline cholangiocarcinoma. This could be the first step to implement in the future new medical treatments (adjuvant chemotherapy) in cases of feline cholangiocarcinoma. Further studies focusing on the prognostic value of CD44 in feline cholangiocarcinoma are warranted.