Histopathology of human renal tumors after laparoscopic renal cryosurgery

Purpose: Laparoscopic renal cryoablation is a nephron sparing treatment alternative for selected patients with small renal tumors. The acute tumoricidal effects of cryosurgery on human renal tumors and in experimental models have been reported previously. For cryoablation to be a viable option in the treatment of renal tumors, it must induce not only acute tissue injury but also sustain permanent tissue necrosis and cellular death, in addition to affording an adequate surgical margin free of viable tumor. We report on the longer term effects of in vivo human tumor tissue destruction by cryosurgery and describe the histopathology of a cryoablated renal lesion. Materials and Methods: Three patients in our series who were treated with laparoscopic renal cryosurgery subsequently underwent radical nephrectomy of the cryoablated renal unit. Results: All patients underwent uneventful cryosurgery. Two patients were found to have positive post-cryosurgery biopsies, while a new, metachronous lesion developed in 1 patient. All 3 patients elected to undergo radical nephrectomy. Mean time from cryosurgery to nephrectomy was 275 days. The cryoablated lesions demonstrated coagulative necrosis as evidenced by numerous histiocytes, cholesterol crystals and dystrophic calcification. There was no evidence of viable tumor within the cryoablated field. Conclusions: The longer term tumoricidal effects of laparoscopic renal cryosurgery in human renal tissue have been demonstrated. However, careful patient selection with lesions less than 3.0 cm and vigilant monitoring of the iceball under strict radiographic guidance are imperative to ensure successful oncological outcomes.