UTILITY OF A PROLIFERATION MARKER IN DISTINGUISHING BETWEEN BENIGN NEVOCELLULAR NEVI AND NEVOCELLULAR NEVUS-LIKE LESIONS WITH MALIGNANT PROPERTIES

In the present study we have investigated the utility of the prolifera tion marker MIB1 in distinguishing between benign naevocellular naevi and naevocellular naevus-like lesions with malignant potential, Percen tages of MIB1 immunoreactivity in the intradermal portion of the lesio ns were determined. In benign congenital and acquired naevi, as well a s in dysplastic naevi, there was no or only a slight intradermal melan ocytic proliferation (0-2%), whereas vertical growth phase melanomas e xhibited a substantial proliferative activity (11-48%). In five cases of naevus-like lesions, which had all relapsed as unmistakable maligna nt melanomas (locally or metastatically) after primary surgery, there was also clear proliferative activity (9-67%). Our findings suggest th at MIB1 may be a useful tool in the routine histopathological examinat ion of problematic naevocellular lesions.