Feline Lymphoma in Focus: Examining the Patterns and Types in Croatia's Pathological Records

Feline lymphoma, a common neoplasm in cats, presents across diverse anatomical sites and is influenced by genetic, immune, environmental, and viral factors. This 15-year retrospective study analyzed feline lymphoma cases from the University of Zagreb's Department of Veterinary Pathology, focusing on epidemiology, anatomical distribution, and immunophenotype. A bimodal age distribution was observed, with peaks at 2-3 and 10-12 years, and breed predispositions were noted in British and European Shorthairs after adjusting for referral frequency. Multicentric lymphoma was the most frequent type observed, followed by alimentary and mediastinal forms. Mediastinal lymphoma predominated in younger cats, whereas alimentary lymphoma was more common in older individuals. Male cats were overrepresented among renal lymphoma cases. Feline leukemia virus/feline immunodeficiency virus (FeLV/FIV) infection showed a strong correlation with mediastinal lymphoma. Overall, B-cell lymphomas were predominant; however, T-cell types were more frequently observed in European Shorthairs. In our study, mediastinal forms were uniformly T-cell, while alimentary and multicentric lymphomas were predominantly B-cell. Temporal trends showed surges in 2016-2017 and 2022-2023, and a decline during the COVID-19 pandemic. These findings highlight the complexity of feline lymphoma and underscore the need for tailored diagnostic and therapeutic strategies.