Vulvar intraepithelial neoplasia of low grade: a challenging diagnosis.

The authors reviewed 21 cases of "mild vulvar atypia" diagnosed from 1981 to 1990. The first 16 cases were diagnosed as hyperplastic dystrophy with mild atypia according to the 1976 ISSVD Classification of Vulvar Disease, while the last five cases were diagnosed as vulvar intraepithelial neoplasia grade I (VIN I). The review of the specimens was made by the same pathologist who gave the initial diagnosis and by a dermatopathologist unaware of the initial diagnosis. Both reviewers used the 1986 and 1989 ISSVD terminologies. The presence of "mild atypia" was confirmed in only four of the 21 specimens, that is in 19% of the cases, and two of them were found in the context of patients suffering from a lichen planus. These findings show that the diagnosis of mild atypia in vulvar tissues is a challenge and that mild vulvar atypia cannot be automatically considered a VIN I.