Hypereosinophilia associated with transitional cell carcinoma in a cat

A 14-year-old spayed female domestic shorthair cat was evaluated because of an abdominal mass and eosinophilia. Widely disseminated, transitional cell carcinoma of the urinary bladder was diagnosed histologically. To further characterize the eosinophilia, eosinophils were separated from other leukocytes and cultured in vitro. Harvested cells were evaluated for density and for in vitro survivability. Results of these tests, hyperplasia of bone marrow eosinophil precursors, and lack of tumor tissue eosinophilic infiltrates suggested that an eosinophilopoietic stimulus of undetermined origin was likely the cause of this cat's hypereosinophilia.