Histopathology of the frozen prostate. The microscopic bases of prostatic carcinoma cryoablation.

SUMMARY In the last few years percutaneous cryoablation surgery of the prostate has been reintroduced as an alternative means to treat prostatic carcinoma. Advantages of the technique include local effectiveness in eradicating tumors, minimal morbidity rate and lower costs when compared to radical surgery. We report a study documenting the histopathological changes seen in 317 biopsy specimens obtained from 30 patients (age range 59- 83 years, median 73 years) treated with cryosurgical ablation for prostate cancer. Pre- and postoperatory assessment was inclusive ofplain clinical, laboratory and instrumental data (digital rectal examination, transrectal ultrasound scan, serum prostatic specific antigen concentration) and systematic biopsies obtained from conventional and modified prostate sextants. Fifteen patients had tumors extending through the prostate capsule (pT3 and pT4). Six patients had stage pTl tumors and 9 had stage pT2. Tissues were sampled at 3, 6 and between 12-18 months postoperatively. The histologic findings, in decreasing order of frequency, were: full core fibrosis, necrosis, granulation tissue, basal cell hyperplasia, cell swelling, hemosiderin deposits, chronic inflammation, thick nerves and prostatic hyperplasia. Necrosis was ofthe coagulative type, sometimes associated with nuclear debris, and seen at relatively short interval from cryotherapy. Fibrosis with hyaline qualities was seen especially at 12-18 month interval. The presence ofnecrosis, as well as granulation tissue, hemosiderin deposits and cell swelling, strongly correlate to intervals from cryosurgical ablation. Residual tumor tissue was focal (0.5 -1 mm) and recognizable in 9 cores from 4 patients (13.3%) sampled especially from the prostatic apex. Incipient tumor necrosis was seen in 11 cores, without particular distribution. These findings indicate that cryosurgery results in distinctive changes in both tumoral and nontumoral prostate tissue. Knowledge ofthe histopathologic patterns is important since it provides the clinicians with information on treatment efficacy or failure, and could assist in the selection of larger groups of patients eligible to cryosurgical ablation.