PATHOLOGY

Should the diagnosis of benign prostatic hyperplasia be made on prostate needle biopsy?
Viglione MP, Potter S, Partin AW, Lesniak MS, Epstein JI
Department of Pathology, The Johns Hopkins Medical Institutions,
Baltimore, Maryland, USA.
Hum Pathol. 2002; 33:796-800

• Purpose: Pathologists frequently sign out benign prostate needle biopsies as “benign prostatic hyperplasia” (BPH). There are no data indicating that a diagnosis of BPH on biopsy correlates with either gland weight or with the International Prostate Symptom Score (IPSS) used to measure urinary obstructive symptoms.
• Material and Methods: The authors examined biopsies for average percentage of glands and average percentage of glands with papillary infolding per case, maximum percentage of glands and maximum percentage of glands with papillary infolding per core per case, and presence of any stromal nodules per case. BPH was measured in 2 ways: (1) IPSS grouped into 3 categories (mild, moderate, severe) and (2) prostate weight at radical prostatectomy in men with limited cancer. IPSS was classified as follows: mild (n = 12), moderate (n = 13), and severe (n = 10).
• Results: There was no correlation with IPSS and any of the histologic features measured. For the 41 radical prostatectomy specimens, the average weight was 65.3 g (median, 56.0 g, range, 22 to 117 g). There was no correlation between gland weight and the average or maximum percentage of glands, or average or maximum percentage of glands with papillary infolding. Stromal nodules on biopsy correlated with gland weight. In the 30 cases without stromal nodules on biopsy, the mean gland weight was 51.4 g. In the 11 cases with stromal nodules on biopsy, the mean gland weight was 77.4 g (P = 0.0125). However, stromal nodules were not specific for a large prostate (i.e., a 15 g prostate had stromal nodules on biopsy).
• Conclusions: With the exception of stromal nodules found on biopsy, histologic findings on biopsy are not specific for either clinical or pathologic BPH. Thus benign prostate biopsies should be signed out merely as “benign prostate tissue”.
  
  
• Editorial Comment
  The diagnosis of “benign prostatic hyperplasia” (BPH) is not uncommon on pathology reports. Most of the times, however, there is no correlation with prostatism. Why does it happen? There are 2 main reasons. The first is related to erroneous diagnosis of benign prostatic hyperplasia. Purely stromal nodules are easily diagnosed by pathologists. Mixed (glandular and stromal) nodules are difficult to diagnose on needle biopsies. Papillary infolding is not a criterion for the diagnosis. The criterion is subtle and depends on the microscopy of the stroma intervening the glands. Most of the times mixed nodules are erroneously diagnosed. The second reason relates to the prostate zone biopsied. Unless specified, the needle biopsy is from the peripheral zone of the prostate, which rarely shows BPH. In 378 radical prostatectomies, Kerley et al. (J Urol Pathol. 1997; 6:87-94) found 57 prostates (15.1%) with nodules in the peripheral zone. Another point to consider is the fact that these nodules in the peripheral zone represent a microscopic finding and are not related to prostatism. In conclusion, pathologists should not have aversion to report “benign prostate tissue”.

Dr. Athanase Billis
Chair, Department of Pathology
State University of Campinas, Unicamp
Campinas, São Paulo, Brazil