From what you have reported, it would appear that IF it is bladder cancer, they think it might be transitional cell carcinoma, which is the most common type of bladder cancer. Your biopsy and pathology report will determine this. It is extremely unlikely that it is related to your lymphoma.
Unfortunately, it is possible and not uncommon to have more than one type of cancer in your lifetime. My bladder cancer came more than 10 years after breast cancer and had nothing to do with it.
If it is bladder cancer, it can be very curable. It is better, of course, to catch it as early as possible, but most cancers have been there a while before they are found, so it is very likely that yours, IF IT IS CANCER, will be very treatable
Sara Anne