The Relationship Between Epidermal Mitotic Density, Atypical Mitotic Figure Density, Breslow Depth, Ulceration, and Dermal Mitotic Rate in Cutaneous Melanoma: A Retrospective Cohort Study

Abstract

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.

Keywords: death; epidermal mitotic density; index; malignant melanoma; metastasis; mitoses; mitotic count; prognosis; recurrence; sentinel lymph node biopsy.