Objective histopathologic grading of cutaneous malignant melanomas by stereologic estimation of nuclear volume. Prediction of survival and disease-free period.

Modern stereologic techniques enable unbiased and shape-independent estimation of the three-dimensional nuclear volume (Vv). This study investigates the prognostic impact of Vv in 47 patients with malignant melanomas (10 years of follow-up) and compares Vv to traditional prognostic parameters and two-dimensional morphometric estimates. The averaged Vv was 226 microns3 and 457 microns3 in Stage I and II melanomas, respectively. The Vv was significantly increased in the case of ulceration, nodular melanoma, and Clark's level greater than III. The Vv showed only poor correlation to two-dimensional morphometric estimates. Cox regression analysis indicated Vv to possess excellent prognostic information, only rivaled by tumor ulceration, the latter being a 100% predictor of metastatic spread. Histologic type, Clark's level of invasion, tumor thickness (according to Breslow), and patient sex were without independent prognostic significance, which may be due to attributes of the small data base. It is concluded that Vv may be a powerful prognostic indicator in cutaneous melanomas, suitable for objective malignancy grading. The clinical and prognostic value of nuclear Vv needs further investigation in a larger and contemporary series of patients with malignant melanomas.