Renal lymphoma is an aggressive form of feline lymphoma in which cancer cells infiltrate one or both kidneys. It typically involves large, rapidly dividing malignant lymphocytes and frequently affects both kidneys simultaneously. A particularly concerning feature of this form is its high tendency to spread to the central nervous system — approximately 40% of affected cats will develop CNS involvement, which can cause neurological signs such as seizures or behavioural changes. Cats may present with enlarged kidneys detected on physical examination, along with weight loss, poor appetite, increased thirst and urination, and potentially signs of kidney failure. The overall prognosis is poor compared to other feline lymphoma types, and chemotherapy protocols must account for compromised kidney function.