Melanosis of the vulva. A clinical simulator of malignant melanoma.

Eight patients with melanosis of the vulva are presented in order to illustrate the characteristic clinical and histopathologic features of the condition. Despite clinical features that may be indistinguishable from those of malignant melanoma, the patchy pigmentation of melanosis that is seen mostly on the vulva, but also on the penis, shows wholly different histologic changes than those of melanoma, namely, a slightly increased number of typical melanocytes arranged as solitary units at the dermal-epidermal junction of a hyperpigmented epidermis. It is important to identify melanosis of the vulva for what it is, because overdiagnosis of it as malignant melanoma may result in needless radical surgery.