Malignant lymphoma, also known as lymphosarcoma, is cancer affecting the lymphatic system. It can occur in any breed of cat, including Maine Coons. Lymphoma is most commonly diagnosed in middle-aged to older cats, but it can also occur in younger cats. Signs of lymphoma in cats may include weight loss, loss of appetite, vomiting, diarrhea, difficulty breathing, and swelling of the lymph nodes. If you suspect that your Maine Coon may have lymphoma, it is crucial to have them inspected by a veterinarian as soon as possible. Lymphoma can be treated with chemotherapy, but the prognosis relies on the stage of cancer and the cat’s overall health.