Abstract

BACKGROUND
We developed a new processing method for extended prostate needle biopsy, and evaluated diagnostic utility of routine immunohistochemistry in 1,000 consecutive unselected cases of transrectal ultrasound-guided systematic prostate biopsy.
METHODS
Four to five biopsy cores were embedded in one paraffin block. All the biopsy cores were immunohistochemically stained with basal cell markers.
RESULTS
The new sample processing method was technically perfect for making a diagnosis from extended prostate needle biopsy. Among 1,000 cases, there were 323 cases (32.3%) of adenocarcinoma, 5 cases of other malignant tumors, 9 cases of high-grade prostatic intraepithelial neoplasia without a carcinoma, and only 8 cases of atypical small acinar proliferation. Among the 323 cases of adenocarcinoma, there were 38 cases (11.8%) of microcarcinomas <0.1 cm and 101 cases (31.3%) of small adenocarcinomas <0.3 cm in length. In the needle biopsy specimens, 59 cases (18.3%) were classified as clinically insignificant carcinomas. Among them, 37 cases underwent radical prostatectomy, which turned out to be clinically significant carcinomas in 24 cases (64.9%).
CONCLUSIONS
Routinely performed immunohistochemistry combined with the new sample processing method is very effective for detecting microscopic carcinoma foci as well as differentiating carcinoma from benign conditions mimicking cancer.

• Keywords: Prostate;Prostatic neoplasms;Needle biopsy;Immunohistochemistry