Histology of lichen sclerosus varies according to site and proximity to carcinoma

To investigate why vulvar but not extragenital lichen sclerosus is associat ed with squamous cell carcinoma, we performed a histologic study of extrage nital lichen sclerosus, vulvar lichen sclerosus without carcinoma, and vulv ar lichen sclerosus with carcinoma adjacent to and distant from the carcino ma. We compared epidermal thickness, rete ridge length, mitotic activity, a typia, dermal collagen change, dermal inflammation, and presence of other d ermatoses in 30 women in each group, Extragenital lichen sclerosus showed t hinner epidermis (mean thickness of 0.13 mm versus 0.41 mm; P < 0.0005), sh orter rete ridges (P = 0.0001), more dermal edema (P = 0.16), and absence o f associated dermatoses of spongiotic dermatitis and lichen planus (P < 0.0 05) compared with vulvar lichen sclerosus. The epidermal thickening seen in vulvar lichen sclerosus was indistinguishable from lichen simplex. chronic us. Vulvar lichen sclerosus without carcinoma was generally similar to that distant from carcinoma. Vulvar lichen sclerosus adjacent to carcinoma show ed increased epidermal thickness (0.61 turn versus 0.26 mm; P < 0.005), mor e dermal fibrosis (P < 0.0005), more inflammation (P < 0.0005), and more si mplex (differentiated) vulvar intraepithelial neoplasia (18 cases versus 1 case; < 0.0005) compared with that distant from carcinoma. We concluded tha t (1) the classic histologic features of lichen sclerosus are seen in both vulvar and extragenital sites; (2) vulvar lichen sclerosus without associat ed carcinoma has a mean epidermal thickness more than three times that of e xtragenital lichen sclerosus; (3) the epidermal thickening is histologicall y indistinguishable from lichen simplex chronicus; (4) there is a tendency for vulvar lichen sclerosus to have a more sclerotic and inflamed dermis; ( 5) lichen sclerosus 10 mm from cancer is more similar to vulvar lichen scle rosus without carcinoma than lichen sclerosus. 1 mm from carcinoma; and (6) lichen sclerosus adjacent to carcinoma tends to show exaggerated epidermis thickness, basal atypia, and loss of the edematous-hyaline layer.