A 65-year-old man recently retired after many years
in a job that involved exposure to aniline dyes, including β-naphthylamine. One month ago, he had an episode of hematuria that was not accompanied by abdominal pain. On physical examination, there are no abnormal findings. Urinalysis shows 4+ hematuria, and no ketones, glucose, or protein. Microscopic examination of the urine shows RBCs that are too numerous to count, 5 to 10 WBCs per high-power field, and no crystals or casts. The result of a urine culture is negative. Cystoscopy is performed, and biopsy of a lesion reveals the microscopic appearance in the figure. Which of the following neoplasms is he most likely to have?