Overexpression of Wild-type p53 in Lichen Sclerosus adjacent to Human Papillomavirus-negative Vulvar Cancer

Human papillomavirus is a risk factor for vulvar cancer, whereas human papillomavirus-negative late onset vulvar carcinoma is associated with the dermatologic condition, lichen sclerosus. Human papillomavirus E6 protein targets TP53 for degradation and by inference it has been assumed that human papillomavirus-negative vulvar cancer is dependent upon the acquisition of p53 somatic mutations and subsequent allelic loss. To investigate this, TP53 expression, loss of heterozygosity, and p53 genomic sequence were examined in 29 cases of human papillomavirus-negative vulvar carcinoma with adjacent lichen sclerosus. We examined 37 cases of lichen sclerosus without vulvar carcinoma, 10 cases of nongenital lichen sclerosus, and 12 cases of normal vulvar epithelium served as controls. TP53 was evident in 72% of vulvar carcinoma, 48% in epithelium adjacent to vulvar carcinoma, but was minimal in normal samples. When lichen sclerosus cases were selected to exclude samples with absolutely no TP53 expression through probable failed antigen retrieval or homozygous p53 loss the number of epithelial cells expressing TP53 increased progressively from nongenital lichen sclerosus to lichen sclerosus without vulvar carcinoma, then to lichen sclerosus with vulvar carcinoma (p