Recurrent primary vulvovaginal malignant melanoma arising in melanoma in situ--the natural history of lesions followed for 23 years.

Multifocal melanoma and melanoma in situ of the vulva and vagina are uncommon lesions, and our understanding of their natural history is limited. Vulvovaginal melanoma appears to be biologically different from cutaneous melanoma and has more in common with mucosal melanoma. A 60-year-old woman presented in 1977 with a pigmented vulvar lesion. Histologic examination revealed melanoma in situ associated with focal invasive melanoma. She re-presented with recurrent primary melanomas arising in melanoma in situ in 1990 and 1998 and died of widespread metastatic melanoma in 2000. Melanoma in situ of the vulva and vagina is rare and appears to have a relatively slow but definite progression to invasive melanoma. All suspicious pigmented lesions in this region should be biopsied, and if multifocal in situ melanoma is identified, vulvo(vagin)ectomy should be considered.