AGMINATED INTRADERMAL SPITZ NEVI ARISING ON AN UNUSUAL SPECKLED LENTIGINOUS NEVUS WITH LOCALIZED LENTIGINOSIS - A CONTINUUM

We report an 18-year-old boy with a congenital pigmented lesion measur ing 2 x 6 cm on his right thigh. About a third of the lesion was compo sed of numerous lentiginous macules superimposed on histologically nor mal and clinically nontan skin; in the remainder of the lesion, severa l macules and papules with histologic features of junctional and compo und nevi were superimposed on clinically normal skin, which had a lent iginous pattern histologically. Some years later, eruptive intradermal Spitz nevi developed at one corner of the lesion. The combined clinic al and histological features of the lesion fulfill descriptions for bo th segmental lentiginosis and an unusual variant of speckled lentigino us nevus. Our case points out the limitations of using strict diagnost ic criteria to define speckled lentiginous nevus and offers an opportu nity to consider the natural history of the lesion as a continuum from lentigines to melanocytic nevi. Moreover, the presence of eruptive in tradermal Spitz nevi arising within the area of speckled lentiginous n evus lacking a distinct tan background, suggests the possibility that the entire area of the lesion per se constitutes an environment where development of nevi is enhanced.