- Malignant melanoma - the most aggressive form of skin cancer. Occurs most often in blonde people with white skin and blue eyes. Melignant lesions may occur on preexisting (congenital nevi, dysplastic nevi) or free skin. The main signs of malignant transformation of a benign nevus pigment are: increase in the surface and depth, irregular borders, uneven pigmentation (darker areas alternanad with more open areas), the occurrence of ulceration or spontaneous bleeding. Therapy consists of wide excision of the tumor and lymph node abscission.