Can pathologists accurately and reliably diagnose PIN?

Short for prostatic intraepithelial neoplasia, PIN is a condition in which some prostate cells have begun to look and behave abnormally. In some cases, PIN can progress to cancer. The condition is usually diagnosed following a prostate biopsy or surgery for benign prostatic hyperplasia (BPH). But the diagnosis, which is based on a pathologist’s reading of the tissue sample, is rather subjective, resulting in large differences in the reported incidence of PIN.

To study the magnitude of overdiagnosis, researchers in Virginia reviewed 251 patients who had been diagnosed initially with PIN. The diagnosis was confirmed in 191 cases, meaning that 60 patients who were told they had PIN didn’t have it. A variety of benign conditions were misinterpreted as PIN. Although no cancers were mistaken for PIN, the overdiagnosis of PIN causes concern among both patients and physicians about the possibility of subsequent cancers and may lead to unnecessary repeat biopsies. The rate of overdiagnosis might also account for the variation in the incidence of PIN reported in different publications.

SOURCE: Bostwick DG and Ma J. Over-Diagnosis of High-Grade Prostatic Intraepithelial Neoplasia: A Prospective Study of 251 Cases. BJU International 2007;100:1036–39. PMID: 17922786.