Correlation of DNA ploidy and histologic diagnosis from prostate core-needle biopsies: is DNA ploidy more sensitive than histology for the diagnosis of carcinoma in small specimens?

DNA ploidy has been shown to have prognostic value in adenocarcinoma of the prostate. While occasional benign lesions of the prostate may be associated with a DNA aneuploid status, most aneuploid epithelial proliferations of the prostate are carcinomas. Because of the relationship between aneuploidy and malignancy, DNA ploidy analysis might improve detection of adenocarcinoma in small core-needle biopsy specimens. In this study, DNA ploidy analysis was performed on 186 fresh core biopsies from 32 patients who had undergone transrectal, ultrasonographically directed core-needle biopsies. Ploidy level was determined by Feulgen staining and image analysis with a CAS 200 image analyzer (Becton Dickinson-Cellular Imaging Systems, San Jose, CA). The resultant DNA ploidy levels were compared with the initial histologic diagnosis and subsequent clinical and pathologic follow-up. Nondiploid DNA patterns correlated with a diagnosis of carcinoma on core biopsy in 11 of 16 nondiploid cases and with a final diagnosis of malignancy in 13 of 16 nondiploid cases. Two patients with biopsy proven carcinoma had DNA diploid tumor patterns. Ploidy analysis had a sensitivity of 86.6% and a specificity of 73.7% in predicting the final diagnosis of malignancy. One case interpreted as DNA tetraploid by image analysis revealed seminal vesicle tissue on both the cytologic preparations and the core biopsy. Two DNA aneuploid specimen associated with cores initially read as benign or atypical demonstrated adenocarcinoma either on review of the original core biopsy or the prostatectomy specimen. The final DNA aneuploid specimen revealed acute prostatitis in the core biopsy. DNA ploidy analysis of core biopsy specimens appears to have relatively good specificity and sensitivity for the detection of prostatic carcinoma. Sampling errors appear to be the major cause of false negative results. Inappropriate measurement of seminal vesicle tissue and acute prostatitis can result in false positive results.