Variability in diagnostic opinion among pathologists for single small atypical foci in prostate biopsies.

Pathologists are increasingly exposed to prostate biopsies with small atypical foci, requiring differentiation between adenocarcinoma, atypical small acinar proliferation suspicious for malignancy, and a benign diagnosis. We studied the level of agreement for such atypical foci among experts in urologic pathology and all-round reference pathologists of the European Randomized Screening study of Prostate Cancer (ERSPC). For this purpose, we retrieved 20 prostate biopsies with small (most <1 mm) atypical foci. Hematoxylin and eosin-stained slides, including 10 immunostained slides were digitalized for virtual microscopy. The lesional area was not marked. Five experts and 7 ERSPC pathologists examined the cases. Multirater kappa statistics was applied to determine agreement and significant differences between experts and ERSPC pathologists. The kappa value of experts (0.39; confidence interval, 0.29-0.49) was significantly higher than that of ERSPC pathologists (0.21; confidence interval, 0.14-0.27). Full (100%) agreement was reached by the 5 experts for 7 of 20 biopsies. Experts and ERSPC pathologists rendered diagnoses ranging from benign to adenocarcinoma on the same biopsy in 5 and 9 biopsies, respectively. Most of these lesions comprised between 2 and 5 atypical glands. The experts diagnosed adenocarcinoma (49%) more often than the ERSPC pathologists (32%) (P<0.001). As agreement was particularly poor for foci comprising <6 glands, we would encourage pathologists to obtain intercollegial consultation of a specialized pathologist for these lesions before a carcinoma diagnosis, whereas clinicians may consider to perform staging biopsies before engaging on deferred or definite therapy.

Interobserver variability between expert urologic pathologists for extraprostatic extension and surgical margin status in radical prostatectomy specimens.

Accurate Gleason score, pathologic stage, and surgical margin (SM) information is critical for the planning of post-radical prostatectomy management in patients with prostate cancer. Although interobserver variability for Gleason score among urologic pathologists has been well documented, such data for pathologic stage and SM assessment are limited. We report the first study to address interobserver variability in a group of expert pathologists concerning extraprostatic soft tissue (EPE) and SM interpretation for radical prostatectomy specimens. A panel of 3 urologic pathologists selected 6 groups of 10 slides designated as being positive, negative, or equivocal for either EPE or SM based on unanimous agreement. Twelve expert urologic pathologists, who were blinded to the panel diagnoses, reviewed 40x whole-slide scans and provided diagnoses for EPE and SM on each slide. On the basis of panel diagnoses, as the gold standard, specificity, sensitivity, and accuracy values were high for both EPE (87.5%, 95.0%, and 91.2%) and SM (97.5%, 83.3%, and 90.4%). Overall kappa values for all 60 slides were 0.74 for SM and 0.63 for EPE. The kappa values were higher for slides with definitive gold standard EPE (kappa=0.81) and SM (kappa=0.73) diagnoses when compared with the EPE (kappa=0.29) and SM (kappa=0.62) equivocal slides. This difference was markedly pronounced for EPE. Urologic pathologists show good to excellent agreement when evaluating EPE and SM. Interobserver variability for EPE and SM interpretation was principally related to the lack of a clearly definable prostatic capsule and crush/thermal artifact along the edge of the gland, respectively.