Reliable identification of transition zone prostatic adenocarcinoma in preoperative needle core biopsy

Prostatic adenocarcinomas arising within the transition zone (Tz) are distinct from peripheral zone (Pz) tumors as regards biological aggression and mechanism of extraprostatic extension. Reliable biopsy identification of Tz tumors would allow targeted surgical approaches more likely to preserve erectile function without compromising surgical margins. Previous studies have demonstrated the presence of eosinophilic cytoplasmic granules (prostate secretory granules, or PSGs) after glutaraldehye fixation, with apparent depletion in neoplasia. We investigated PSG content, columnar cells, pale cytoplasm, and luminal secretions of both Pz and Tz tumors in 44 radical prostatectomies (RPs) and 135 biopsies fixed with gluteraldehyde-based fixative. Retention of PSG is characteristic of Tz carcinoma and infrequently seen in Pz tumors, and a combination of PSG greater than 30% with either columnar cells, pale cells, or secretions in biopsies is a reliable marker for Tz origin. When these criteria were prospectively applied to 3929 cases with follow-up RP, 510 Tz tumors were correctly identified on biopsy (sensitivity, 21.4%; specificity, 97.4%). Biopsy-identified Tz tumors had higher volumes (mean, 3.48 versus 1.81 cm(3); P < .001) and higher rates of margin positivity (22.5% versus 17.5%; P = .008) than did Tz tumors not identified preoperatively. Mean Tz tumor length in biopsies was 2.0 mm, with no correlation between tumor volume at RP and tumor length on biopsy. Tz tumors are reliably identified on biopsy, based on a combination of PSG retention with either columnar cells, pale cells, or secretion. Biopsy-identified Tz tumors may not be suitable for active surveillance because of an associated high probability of large tumor volume and increased risk of positive margins at RP.