[880] Retrospective Analysis of Prostatic Adenocarcinomas Scored as Gleason Grade 1 as a Primary or Secondary Grade in Transurethral Resection or Radical Prostatectomy Specimens

RE Jimenez, JP Reynolds, JC Cheville. Mayo Clinic, Rochester, MN

Background: Histologic grading is one of the most important prognostic parameters in prostatic adenocarcinoma (PrAC). The Gleason grading system is based on a spectrum of patterns of tumor differentiation that ranges from 1 to 5. The assignment of a Gleason grade 1 (GG1) to PrAC is exceedingly uncommon and has been discouraged in needle core biopsies. Its use in radical prostatectomy (RP) or transurethral resection (TURP) specimens remains controversial.
Design: All RP and TURP specimens containing PrAC diagnosed at Mayo Clinic between 1992 and 2003 were searched for the presence of a primary or secondary GG1 in the final Gleason score (GS). Tumors were rescored as per traditional and 2005 ISUP Consensus Conference GS guidelines. Other variables recorded were tumor histologic type, size and location, number of tumor foci, pathologic stage, and margin status in RP specimens.
Results: Out of 9403 cases of PrAC present in TURP or RP specimens during the study period, 21 (0.22%), including 10 TURP and 11 RP, were assigned a GG1 either as a primary or secondary grade. No tumor with such a grade was found after 1997. One case was considered to contain only benign prostatic tissue on review of available permanent slides. The remaining 20 cases were all upgraded as follows: One case to GS 2+2, 3 cases to GS 2+3, 12 cases to GS 3+3, 3 cases to GS 3+4. The number of tumor foci ranged from 1 to 5 (mean 1.94, median 1), and the mean and median size of largest tumor focus was 0.36 and 0.3 cm, respectively (range 0.07 to 1.0 cm). Four of the 21 cases had a pseudohyperplastic histology, and 17 were located in the transition zone or anterior prostate. All tumors in TURP specimens represented less than 5% of volume of resected tissue (pT1a). All tumors in RP specimens were organ confined (pT2) with negative margins and negative lymph node status.
Conclusions: Pathologists are not likely to grade PrAC as GG1, even in TURP or RP specimens. At our institution, such a grade has not been used in more than a decade. Small tumor size and anterior/transition zone location may explain the assignment of this grade to tumors in the past. GP1 PrAC are likely extremely rare neoplasms. The fact that a bona fide example of such a tumor was not found in a large series of cases from a tertiary care institution raises doubts about whether they actually exist, or at least whether meaningful prognostic information can be associated to them.
Category: Genitourinary (including renal tumors)

Tuesday, March 23, 2010 1:00 PM

Poster Session IV # 104, Tuesday Afternoon


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