Controversies in prostate pathology: dysplasia and carcinoma in situ.

In recent years we have made great strides in our understanding of various atypical lesions within the prostate. This clarity originated with the recognition that lesions of atypical hyperplasia of the prostate are diverse both in their histology and in their potential relationship to adenocarcinoma. While the possible relationship of adenosis to carcinoma is still somewhat controversial, there has been a growing body of histological, histochemical, and immunohistological evidence demonstrating that intraductal dysplasia (PIN) is closely linked to some forms of adenocarcinoma of the prostate. Whether there are significant differences in the relationship of intraductal dysplasia to clinically detectable peripherally located adenocarcinoma and centrally located incidentally found carcinomas needs additional clarification. Further studies on all forms of atypical hyperplasia are still required to determine their relative risk of developing carcinoma, similar to those that have been recently published on various atypical hyperplastic lesions within the breast. In order for these studies to be successful, better imaging techniques of the prostate must become available to rule out invasive carcinoma already being present when one of the forms of atypical hyperplasia is identified on biopsy. Additional directions of research in the future will also undoubtedly probe the molecular biology of various forms of atypical hyperplasia, in particular intraductal dysplasia and its relationship to carcinoma, although at this time the molecular characteristics of adenocarcinoma of the prostate is still in its infancy.