Unilateral dysplastic nevi associated with malignant melanoma.

A case of dysplastic nevi associated with malignant melanoma was reported. The case was characterized by unilateral distribution of dysplastic nevi. Multiple dysplastic nevi were observed only dorsally on the patient's left upper quadrant. To the best of our knowledge, the report of this form of dysplastic nevi is the first in Japan. In addition, dysplastic nevus cell nests were present in histologic contiguity with intraepidermal proliferation of melanoma in the radial growth phase. Histological evidence suggested that the melanoma in our case had probably been derived from the context of dysplastic nevus.