Lichen sclerosus (LS) is a chronic inflammatory mucocutaneous disease with uncertain etiology. It occurs as white plaque-like lesions mostly in the anogenital skin. Oral mucosal involvement is extremely rare. This study aims to summarize the features of published oral lichen sclerosus (OLS) and two new cases. A systematic search of the English literature from 1955 to 2016 was performed in MEDLINE, Scopus, and Web of Science, and cross-references were searched manually. Search phrases included "lichen sclerosus," "mouth," "oral," "lip," "palate," "floor of mouth," "tongue," "gingiva," "buccal mucosa," and "mouth diseases." Cases with clinical and histopathological confirmation of diagnosis of OLS were included. A total of 41 (39 published and 2 new) histologically confirmed OLS cases were available. The median age of OLS patients was 31 years, and 66% of the patients were female. Most of the OLS lesions were asymptomatic. They were located in the labial mucosa (n = 20), lip (n = 15), buccal mucosa (n = 14), gingiva (n = 12), tongue (n = 12), and palate (n = 7). OLS is rare and typically presents as asymptomatic, white, plaque-like lesions. Malignant transformation of preexisting OLS has not been reported.

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