[Cystic form of kidney cancer. Apropos of a case].

The authors report a case of cystic form of carcinoma of the kidney in a patient who also had a bladder tumour which could have explained the presenting symptom of haematuria. It was the discordance between echotomography and CT scan findings which led the authors to explore the patient surgically. A reassuring result of a frozen section biopsy led to partial nephrectomy even though the cystic mass had thick walls and serosanguinous contents. The actual diagnosis was corrected within 24 hours by the histopathologists who reported a clear cell renal carcinoma. The authors performed an extended nephrectomy which revealed the presence of some malignant cells in the remaining renal fragment. They take this opportunity to review the general problem of the association of carcinoma of the kidney and renal cyst. This case shows how hazardous may be the answer given from frozen section biopsy of a cystic mass in the kidney and how dangerous it is to perform a partial nephrectomy which may leave tumour tissue in place.