Interactive digital slides with heat maps: a novel method to improve the reproducibility of Gleason grading

Abstract

Our aims were to analyze reporting of Gleason pattern (GP) 3 and 4 prostate cancer with the ISUP 2005 Gleason grading and to collect consensus cases for standardization. We scanned 25 prostate biopsy cores diagnosed as Gleason score (GS) 6-7. Fifteen genitourinary pathologists graded the digital slides and circled GP 4 and 5 in a slide viewer. Grading difficulty was scored as 1-3. GP 4 components were classified as Type 1 (cribriform), 2 (fused) or 3 (poorly formed glands). A GS 5-6, 7 (3+4), 7 (4+3), 8-9 was given in 29%, 41%, 19% and 10% (mean GS 6.84,). In 15 cases, at least 67% of observers agreed on GS groups (consensus cases). Mean interobserver weighted kappa for GS groups was 0.43.Mean difficulty scores in consensus and non-consensus cases were 1.44 and 1.66 (p = 0.003).Pattern 4 Types 1, 2 and 3 were seen in 28%, 86% and 67% of GP 4. All three co-existed in 16% (11% and 23% in consensus and non-consensus cases, p = 0.03). Average estimated and calculated %GP 4/5 were 29% and 16%. After individual review, the experts met to analyze diagnostic difficulties. Areas of GP 4 and 5 were displayed as heat maps, which were helpful for identifying contentious areas. A key problem was to agree on minimal criteria for small foci of GP 4. In summary, the detection threshold for GP 4 in NBX needs to be better defined.This set of consensus cases may be useful for standardization.

Implications of the International Society of Urological Pathology Modified Gleason Grading System

“…Conceptually, the change in grade from pattern 3 to pattern 4 would be expected to be reflected in a distinct architectural paradigm shift where cribriform as opposed to individual glands are formed, rather than merely a subjective continuum of differences in size, shape, and contour of cribriform glands pattern 4 carcinomas. 28 In a recent study, which evaluated reproducibility for each Gleason score group under the modified system, there was 68% congruence for Gleason score 7, compared with 27% in 1994, a finding that underscores the importance of the modifications to Gleason pattern 4 definitions.…”

Diagnostic prostate biopsy performed in a non-academic center increases the risk of re-classification at confirmatory biopsy for men considering active surveillance for prostate cancer

“…Challenges surrounding GS interpretation have been well documented, even among uropathologists. 16,17 The agreement in reporting of GS 6 between 15 expert uropathologists and 337 members of the European Network of Uropathology was reported as 71.4% (58.2-89.3%). 18 One of the greatest difficulties lies in reproducibly recognizing small amounts of Gleason pattern 4 in biopsies that otherwise contain only Gleason pattern 3.…”

Significance of Gleason Grading of Low-Grade Carcinoma of the Prostate with Therapeutic Option of Active Surveillance

“…Therefore, we have studied the interobserver reproducibility of glandular fusion (with the options yes or no) in cases of prostate carcinomas GS 6 (pattern 3 + 3) and 7 (pattern 3 + 4) by uropathologically specialized and non-specialized pathologists with the ĸ statistic method similar to other studies [17,18,28,29,30,31]. …”