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Prognostic factors for melanoma include Breslow depth (BD), ulceration, and dermal mitotic rate (DMR). No studies have queried the effect of epidermal mitotic density (EMD) or atypical mitotic figure density (AMD) in an outcome-based assessment. Our objective was to determine if there is a relationship between EMD, AMD, BD, DMR, and ulceration and patient outcomes. This was a retrospective cohort study of 185 cases of thick and thin melanomas. Univariate and multivariate cause-specific regression analysis was performed. There was a positive correlation between EMD and BD ( P  = .0001). The difference between AMD in thick and thin melanomas was statistically significant. For every unit increase in EMD, patients had a 2.8-fold increase in the risk of distant metastasis; however, statistical significance was lost in the multivariate analysis. In adjusted analyses, ulceration, DMR, and BD were associated with outcomes. There were no statistically significant correlations between AMD and outcomes. This study is limited by its small sample size, diminution of the epidermis in some thick melanomas preventing EMD estimates, and reproducibility of mitotic figure counting. EMD and AMD do not seem to have any independent value in multivariate analyses for melanoma. Ulceration, BD, and DMR were significantly associated with outcomes and further solidify these known predictors of prognosis.

Introduction. The identification of mitotic figures is essential for the diagnosis, grading, and classification of various different tumors. Despite its importance, there is a paucity of literature reporting the consistency in interpreting mitotic figures among pathologists. This study leverages publicly accessible datasets and social media to recruit an international group of pathologists to score an image database of more than 1000 mitotic figures collectively. Materials and Methods. Pathologists were instructed to randomly select a digital slide from The Cancer Genome Atlas (TCGA) datasets and annotate 10-20 mitotic figures within a 2 mm2 area. The first 1010 submitted mitotic figures were used to create an image dataset, with each figure transformed into an individual tile at 40x magnification. The dataset was redistributed to all pathologists to review and determine whether each tile constituted a mitotic figure. Results. Overall pathologists had a median agreement rate of 80.2% (range 42.0%-95.7%). Individual mitotic figure tiles had a median agreement rate of 87.1% and a fair inter-rater agreement across all tiles (kappa = 0.284). Mitotic figures in prometaphase had lower percentage agreement rates compared to other phases of mitosis. Conclusion. This dataset stands as the largest international consensus study for mitotic figures to date and can be utilized as a training set for future studies. The agreement range reflects a spectrum of criteria that pathologists use to decide what constitutes a mitotic figure, which may have potential implications in tumor diagnostics and clinical management. [ABSTRACT FROM AUTHOR]