Reliability of diagnosis from Mohs slides: interpersonal and intrapersonal agreement on basal cell carcinoma presence and histological subtype.

BACKGROUND: The success of Mohs micrographic surgery (MMS) depends partly on the correct diagnosis of slides. OBJECTIVES: To determine reliability of diagnosis from Mohs slides. METHODS: This was a prospective study evaluating the reliability of diagnosis from Mohs slides of basal cell carcinoma (BCC) presence, BCC location on the slide and BCC subtype among six raters who independently assessed 50 Mohs slides twice with a 2-month interval. Slides were randomly selected whereby difficult-to-diagnose slides were oversampled. For each slide, a reference diagnosis was established by an expert panel. Cohen's kappa (κ) was calculated to determine levels of agreement interpersonally (rater vs. reference diagnosis) and intrapersonally (rater at T1 vs. T2). Multivariable logistic regression was used to determine independent risk factors for slides with interpersonal discordant diagnosis. The variables studied were BCC presence, whether a slide was scored as easy or difficult to diagnose, review duration of the 50 slides, profession and years of experience in diagnosis from Mohs slides. RESULTS: Interpersonal and intrapersonal agreement were substantial on BCC presence (κ = 0·66 and 0·68) and moderate on BCC subtype (κ = 0·45 and 0·55). Slides that were scored as difficult to diagnose were an independent risk factor for interpersonal discordant diagnosis on BCC presence (odds ratio 3·54, 95% confidence interval 1·81-6·84). CONCLUSIONS: Reliability of diagnosis from Mohs slides was substantial on BCC presence and moderate on BCC subtype. For slides that are scored difficult to diagnose, a second opinion is recommended to prevent misinterpretation and thereby recurrence of skin cancer.

Proliferation markers and DNA content analysis in urinary bladder TaT1 urothelial cell carcinomas: identification of subgroups with low and high stage progression risks.

AIMS: To evaluate whether in situ biomarkers Ki67, mitotic activity index (MAI), p53, mean area of the 10 largest nuclei (MNA10), and whole genome DNA ploidy by flow and image cytometry (FCM and ICM, respectively) have independent prognostic value in urinary bladder urothelial cell carcinomas (UCs). METHODS: Ki67 and p53 immunoquantitation was performed in TaT1 consensus diagnosis UCs. MAI and MNA10 were also determined. Single cell suspensions were stained (DAPI for FCM; Feulgen for ICM). There was enough material for all measurements in 171 cases. Kaplan-Meier curves and multivariate survival analysis (Cox) were used to assess the prognostic value of all features (including classic clinicopathological risk factors, such as stage, grade, multicentricity, carcinoma in situ). RESULTS: Thirteen (7.6%) patients progressed. Of the classic factors, grade was strongly prognostic in univariate analysis, as were all the biomarkers. In multivariate analysis, the strongest independent combinations for progression were MNA10 (threshold (T) = 170.0 micro m(2)) plus MAI (T = 30), or MNA10 (T = 170.0 micro m(2)) plus Ki67(T = 25.0%). p53 (T = 35.2%) plus Ki67 (T = 25.0%) also predicted progression well, with high hazard ratios, but p53 measurements were not as reproducible as the other features. The prognostic value of the quantitative biomarkers exceeded that of the classic risk factors and DNA ploidy. The sensitivity, specificity, positive, and negative predictive values of MNA10/MAI or MNA10/Ki67 at the thresholds mentioned were 100%, 79%, 57%, and 100%, respectively. These feature combinations were also strongest prognostically in the high risk treatment subgroup. CONCLUSIONS: The combined biomarkers MNA10/Ki67 or MNA10/MAI are more accurate and reproducible predictors of stage progression in TaT1 UCs than classic prognostic risk factors and DNA ploidy.