title: Variability in diagnostic opinion among pathologists for single small atypical foci in prostate biopsies.
abstract: 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.
authors.affiliation: Department of Pathology, 11th floor, University Health Network, 200 Elizabeth Street, Toronto M5G 2C4, Canada. theo.vdkwast@uhn.on.ca
authors.forename: Theodorus H
authors.initials: TH
authors.lastname: Van der Kwast
authors.forename: Andrew
authors.initials: A
authors.lastname: Evans
authors.forename: Gina
authors.initials: G
authors.lastname: Lockwood
authors.forename: Doug
authors.initials: D
authors.lastname: Tkachuk
authors.forename: David G
authors.initials: DG
authors.lastname: Bostwick
authors.forename: Jonathan I
authors.initials: JI
authors.lastname: Epstein
authors.forename: Peter A
authors.initials: PA
authors.lastname: Humphrey
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Montironi
authors.forename: Geert J L H
authors.initials: GJ
authors.lastname: Van Leenders
authors.forename: Carl-Gustaf
authors.initials: CG
authors.lastname: Pihl
authors.forename: Ingrid
authors.initials: I
authors.lastname: Neetens
authors.forename: Paula M
authors.initials: PM
authors.lastname: Kujala
authors.forename: Marita
authors.initials: M
authors.lastname: Laurila
authors.forename: Catharine
authors.initials: C
authors.lastname: Mazerolles
authors.forename: Lukas
authors.initials: L
authors.lastname: Bubendorf
authors.forename: Antonio
authors.initials: A
authors.lastname: Finelli
authors.forename: Kemp
authors.initials: K
authors.lastname: Watson
authors.forename: John
authors.initials: J
authors.lastname: Srigley
mesh_terms: D000230:Adenocarcinoma / Q000737:chemistry / Q000175:diagnosis*; D014408:Biomarkers, Tumor / Q000032:analysis; D001706:Biopsy; D003937:Diagnosis, Differential; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D015588:Observer Variation; D011467:Prostate / Q000737:chemistry / Q000473:pathology*; D011471:Prostatic Neoplasms / Q000737:chemistry / Q000175:diagnosis*
chemical_list: D014408:Biomarkers, Tumor