Despite the modest size of the prostate, it accounts for an inordinate amount of disease, resulting in a substantial diagnostic burden for the surgical pathologist.
Benign hyperplasia afflicts the majority of men older than 50 years, but the near-complete replacement of transurethral resections in the past 2 decades by other treatments (eg, 5α-reductase inhibitors, laser therapy, other ablative techniques, and so on) has greatly reduced the number of such tissue specimens for examination. However, prostate cancer persists as the most common nonskin cancer in men, and early detection efforts result in more than 1 million biopsies annually; there are 10 or 12 needle cores per typical biopsy, accounting for more than 10 million cores for evaluation. Furthermore, an estimated 100,000 radical prostatectomies are performed in the United States, creating an additional burden for pathologists. There are a multitude of variants of benign hyperplasia as well as mimics of prostate cancer, compounding the diagnostic challenge.
This issue of Pathology Case Reviews has 2 goals: first, to review current controversies in prostate pathology, including cancer grading, tissue handling, and use of immunohistochemical markers and, second, to describe some of the most common contemporary diagnostic dilemmas through the use of focused case studies. The report on grading presents the relative strengths and weaknesses of the classic Gleason grading system—still the most widely used in the United States and world today—in comparison with the ISUP 2005 Modified Gleason grading system. The review of tissue handling addresses quality control for biopsies, an area of growing interest among urologists and pathologists alike. The article on immunohistochemical stains describes the practical relative merits, applications, and limitations of these critical techniques for diagnosis and prognosis, including TMPRSS2:ERG staining.
The spectrum of variants of nodular hyperplasia and its mimics is addressed in a case report of florid basal cell hyperplasia. Another case study presents a thorough and balanced discussion of the current understanding of intraductal carcinoma, a relatively rare but clinically significant finding beset with confusion owing to varying diagnostic definitions. By way of contrast, another review addresses the criteria and significance of high-grade prostatic intraepithelial neoplasia. The spectrum of neuroendocrine differentiation is evaluated in a report emphasizing the importance of small cell carcinoma. Finally, the current state of understanding of atypical small acinar proliferation suggestive of malignancy is, appropriately, presented by Iczkowski, the first to describe this common and difficult finding in his seminal report from 1997.
I am grateful to the editor of Pathology Case Reviews, Dr Silverberg, for allowing me and my urologic pathology colleagues the opportunity to assemble this collection of reports. We hope that they are a source of diagnostic enlightenment in grappling with often-difficult prostate tissue specimens.