Gleason Grading of Prostatic Carcinoma

Lars Egevad, M.D., Ph.D.
Associate Professor of Pathology
Karolinska Hospital
Stockholm, Sweden

William C. Allsbrook, Jr., M.D.
Professor Emeritus of Pathology
and Surgery (Urology)
Medical College of Georgia
Augusta, Georgia

Jonathan I. Epstein, M.D.
Professor of Pathology, Urology, and Oncology
The Reinhard Professor of Urologic Pathology
Director of Surgical Pathology
The Johns Hopkins Hospital
Baltimore, MD

Prostatic carcinoma with areas of crush and cautery artifacts should not be graded. These artifacts are particularly common at the margins of total prostatectomy specimens but crush artifacts may also occur in core biopsies. At times, it may be difficult to determine whether the artifacts are due to crush or cautery or a combination of both. In prostatectomies, the artifacts are greatest at the periphery with transitions to deeper tissue which is not distorted. There may be partial or complete collapse of glandular lumina. Consequently, a pattern 3 might be misinterpreted as pattern 4 or 5. Evaluation of the non-distorted tissue deep to the transition areas usually provides reassurance that one is dealing with artifact.

Prostatic carcinoma which shows the effect of androgen deprivation therapy (ADT) should not be graded. Most commonly, ADT causes decreased to absent glandular lumina. ADT may also cause cytoplasmic vacuolization, at times extensive, as well as pyknotic nuclei. In some positiveces, only individual scattered carcinoma cells, easily confused with inflammatory cells and requiring immunohistochemical stains for positive identification, may remain. Here again, a pattern 3 carcinoma following ADT might easily be misinterpreted as pattern 4 or 5. If there are areas of a tumor treated with ADT that do not show treatment effect and resemble ordinary untreated cancer, that component of the tumor may be assigned a Gleason score, but it should be noted that the area graded is an area that does not show treatment effect.

Prostatic carcinoma which has been treated with radiation therapy should generally not be graded. The diagnosis of prostatic carcinomaa following radiation relies on recognition of an infiltrative growth pattern. In moderate-severe radiation effect, glandular lumina may be decreased to absent, leading to overgrading. Some carcinomas, or areas of carcinoma, following radiation therapy, have little or no radiation effect, and are indistinguishable from the pre-radiation carcinoma. A decision can be made to grade these areas. If such a decision is made, it is obviously critical for the urologist to know that the areas that are being graded are those which do not have histologic evidence of response to the radiation therapy.