The significance of intraluminal prostatic crystalloids in benign needle biopsies

Intraluminal prostatic crystalloids (IPC) are more common in prostate cancer acini than in benign acini. This study was undertaken to evaluate the hypothesis that crystalloids seen in a benign biopsy may indicate an increased risk of a concomitant prostatic carcinoma. A total of 600 patients underwent more than one prostate biopsy. For 394 patients the results of the biopsy were either negative or positive for prostate cancer. After exclusion of patients whose biopsy results were considered negative but coded as high-grade prostatic intraepithelial neoplasia or were suspicious for cancer or whose slides were unavailable for review, 331 patients remained. Biopsy results for these patients were evaluated for the presence of IPC. Also, 18 completely-embedded benign prostates from cystoprostatectomy specimens from patients with bladder cancer were evaluated for the presence of IPC. Seven hundred twenty-five biopsy specimens were reviewed; 51 (7%) contained crystalloids. Thirty-two of 634 (5%) benign biopsy specimens and 19 of 91 (21%) prostatic carcinoma biopsy specimens contained crystalloids. Sixteen of 331 patients (5%) had crystalloids in the initial benign biopsy specimen; 6 patients subsequently were determined to have carcinoma (38%), and 10 continued to have negative results (62%). Three hundred fifteen initial benign biopsies did not show crystalloids; 83 (26%) patients were subsequently diagnosed as having prostatic carcinoma (p = 0.238, Fisher's Exact Test, chi-square test). The IPC were found in 5 of 18 cystoprostatectomy prostates (28%). In this study, the presence of IPC on the initial biopsy specimens was not a significant risk factor for a subsequent diagnosis of prostate cancer. The IPC were not uncommon in prostates without cancer.