(235) Prognostic Value of Nuclear Grading of Cutaneous Melanoma: The UNC Chapel Hill Method

Track
Clinical Studies
Abstract

McGovern (1970) showed that melanoma nuclear grade significantly correlated with survival, and nuclear grade is used in various cancers other than melanoma.  We sought to reproduce McGovern’s nuclear grade as a histologic indicator of melanoma prognosis. This is a retrospective analysis of 544 melanomas from 2020-2023 with median follow-up time of 411 days; 89 patients progressed, and 22 died of disease. A dermatopathologist assigned nuclear grade by microscopic evaluation of nuclear size, membrane contour, character of nucleoli, and chromatin arrangement. Grade 1 resembles nevus nuclei, Grade 3 shows extremes of nuclear abnormalities, and Grade 2 represents abnormalities between Grades 1 and 3. Kaplan-Meier survival curves were utilized to determine progression-free survival based on nuclear grade, which demonstrated a significant difference between Grade 3 and Grades 1 and 2 (p<0.003). Statistical analyses were conducted in R, using Student’s T-test, Chi-sq, or Kruskal Wallis tests. Grade 3 vs. Grade 1 lesions had older mean age and increased Breslow thickness, mitoses, ulceration, overall stage, and death from disease (each p<0.05). In a univariate Cox proportional hazard model, Grade 2 (HR: 1.7; 95% CI: 0.7-4.0) and Grade 3 (HR: 3.6; 95% CI: 1.5-8.4) lesions were associated with increased probability of progression vs. Grade 1 lesions. Adjusting the covariates noted above attenuated the hazard ratios for nuclear grades 2 and 3 to 1.2 (95% CI: 0.5-2.9) and 1.7 (95% CI: 0.7-4.2), respectively. Studies with longer follow-up and more outcomes are needed to assess nuclear atypia as an independent predictor of melanoma progression or mortality.

Published in: ASDP 61st Annual Meeting

Publisher: The American Society of Dermatopathology
Date of Conference: November 4-10, 2024