[Malignant blue nevus in Ota's nevus].

A 21-year-old Caucasian woman with congenital nevus of Ota developed a subcutaneous tumor below the lacrimal sack within the area of discoloration. The tumor, located subcutaneously, has been present for 4 years. Histologically, parts of the tumor showed neuroid structures as well as those like cellular blue nevus. In one part, however, malignant transformation features could be found.