p53 immunostaining in lichen sclerosus is related to ischaemic stress and is not a marker of differentiated vulvar intraepithelial neoplasia (d-VIN)

AIM: To analyse p53 immunoreactivity in 207 biopsy specimens of lichen sclerosus (LS) and "differentiated vulvar intraepithelial neoplasia" (d-VIN), a postulated precursor lesion for LS-associated vulvar squamous cell carcinoma (SCC), which is characterized by atypical basal keratinocyte proliferations with p53+ basal/suprabasal keratinocyte nuclei. METHODS AND RESULTS: Forty early, 78 classic, 30 hypertrophic vulvar LS, 26 paediatric vulvar and penile LS, 33 vulvar LS-associated SCC and 30 vulvar/penile control specimens were examined for p53 expression and the presence of d-VIN. Nuclear p53 staining was observed in 175/207 LS biopsy specimens. Eighty percent of early and 69% of paediatric LS showed discontinuous/continuous p53 staining in basal keratinocytes. Classic LS showed no p53 staining in 17%, discontinuous basal keratinocyte staining in 20%, continuous basal keratinocyte staining in 58%, basal/suprabasal staining in 5%. Hypertrophic LS revealed basal keratinocyte staining in 32% and basal/suprabasal staining in 61%. p53 staining was associated with sclerosis of blood vessels and dermis, lymphoid infiltrates, vasculitis and hypertrophic LS. d-VIN was seen in 2% of LS alone and in 24% of LS-associated SCC. CONCLUSION: d-VIN in LS is rare, while p53 staining is common and best explained as an ischaemic stress response due to poor oxygenation, vasculitis and inflammation rather than as a marker of a precancerous lesion in LS.