Nuclear morphometry of MIB-1 positive and negative tumor cells in primary and metastatic malignant melanoma of the skin.

The purpose of this study was the evaluation of nuclear area, nuclear axis ratio, perimeter and roundness of nuclei of tumor cells with and without Ki-67 antigen expression (demonstrated immunohistochemically using MIB-1 antibody) in primary and metastatic malignant melanoma of the skin. The parameters were further analyzed with respect to their association with the depth of malignant invasion according to Clark [7] and tumor thickness according to Breslow [6]. 142 malignant melanomas (53 primary and 89 metastatic), were assessed employing a computerized image analyzer Quantimet 600S (Leica). The mean nuclear area of MIB-1 positive nuclei was significantly larger than that of the negative ones (p < 0.0001) both in primary and metastatic malignant melanoma. In comparison to the primary melanoma the nuclei of metastatic melanoma cells had a larger area and were more rounded, while the MIB-1 positive nuclei additionally showed a greater degree of polymorphism of their area and shape. With growing invasion thickness according to Breslow and increased Clark's level, the mean nuclear area of tumor cells increased, and their shape became more round. The MIB-1 positive tumor cell nuclei of primary melanomas with metastases were significantly out of round in comparison to primary melanomas without metastases. The results indicate an association between the area and shape of melanoma cell nuclei and the presence of metastases, and between the nuclear area of tumor cells and such factors related to poor prognosis as the depth of invasion and the tumor thickness.