Q. A 60-year-old male patient has a history of taking cyclophosphamide for the treatment of his rheumatoid arthritis. He has recently noticed the presence of painless hematuria. On physical examination, the patient is alert and oriented, with a temperature of 37°C, a pulse of 70 bpm, a blood pressure of 120/80 mmHg, and a respiratory rate of 18 breaths per minute. There is no peripheral edema. Abdominal examination is benign, with no masses or organomegaly. Which of the following is the most likely diagnosis?