The value of perineal punch biopsy in estimating the histological grade of carcinoma of the prostate

The degree of accuracy of the histological grade of carcinoma of the prostate obtained by perineal punch biopsy was analyzed by comparing the histological findings with those of radical prostatectomy specimens. Biopsy specimens of 97 of 100 patients who underwent radical prostatectomy between 1969 and 1979 were reevaluated. In 43% of the cases, perineal punch biopsy revealed a uniform architectural pattern, which was classified as well-differentiated adenocarcinoma in 21 cases and poorly differentiated adenocarcinoma in 22 cases. However, of the 21 cases determined by biopsy to be uniformly well-differentiated adenocarcinomas, only seven (33.3%) were confirmed by evaluation of the radical prostatectomy specimens. A uniform, poorly differentiated adenocarcinoma was ultimately found in only five operative specimens of the 22 patients with this preoperative diagnosis. As one case clearly demonstrated, multifocal origin of carcinoma of the prostate is the main source of the frequently occurring error encountered with perineal punch biopsy in determining the grade of differentiation.