Oral linear epidermal nevus: a review of the literature and report of two new cases.

Linear epidermal nevus (LEN) is a sporadic hamartomatous lesion of the skin due to the proliferation of clones of embryonic ectodermal cells, which are arranged according to a typical linear configuration known as Blaschko's lines. Oral involvement of LEN is very rare and few cases have been reported in the medical literature. We report two new cases of LEN with exclusive oral involvement, which presented with the typical unilateral or midline distribution. Oral LEN presents as an exophytic lesion with well defined borders and a verrucous or papillary surface which correspond, histologically, to epithelial papillomatosis with a moderate degree of hyperkeratosis and acanthosis. Oral LEN appears mainly at birth, grows slowly during childhood and stabilize by adolescence. Localized lesions do not show any recurrence after surgical removal but widespread lesions seem to have more risk of recurrence and are more difficult to manage. Functional problems and malignant transformation have not been reported.