PAPILLARY TRANSITIONAL-CELL CARCINOMA ARISING IN A CALYCEAL CYST AND MASQUERADING AS A RENAL CYST

We report the case of a 74-year-old man with a papillary transitional cell carcinoma, grade 1-2/3, growing within a bilobated calyceal cyst, measuring up to 8.5 cm in diameter, and masquerading as a simple rena l cyst. The cyst was lined by atrophic simple and transitional epithel ium and showed intracystic hemorrhage. Leakage of blood into the calyx was probably the cause of the hematuria for which the patient present ed. However, with retrograde pyelography and careful gross examination of the excised kidney, no communication of the pyelocalyceal system w ith the cyst could be identified. By ultrasound examination and comput erized tomographic scan the lesion showed several small renal cysts, m easuring up to 1.1 cm in diameter, as well as several hepatic parenchy mal cysts. To our knowledge, this is the first report of a papillary t ransitional cell carcinoma arising from a cyst of calyceal origin.