Benign alveolar ridge keratosis (oral lichen simplex chronicus): A distinct clinicopathologic entity.

Benign alveolar ridge keratosis is a common benign white papule or plaque that occurs on the keratinized gingiva of the maxillary or mandibular alveolar ridge that is probably traumatic/frictional in origin, with characteristic histologic features, similar to those of lichen simplex chronicus of the skin. This is a retrospective study of 108 consecutive specimens displaying characteristic histopathologic features of benign alveolar ridge keratosis accessioned during a 36-month period. There was a male:female ratio of 3.7:1. It occurred on the attached gingiva, with the retromolar area and the edentulous alveolar ridge involved in 51% and 49% of cases, respectively; 19% were bilateral and all bilateral cases were on the retromolar pad. Detailed clinical information was available on 27 cases by a mail-in questionnaire. Histologically, the lesions were characterized by moderate to marked hyperorthokeratosis and wedge-shaped hypergranulosis. The epithelium exhibited slight surface papillomatosis and acanthosis in the form of long, tapered rete ridges that frequently anastomosed at the base. There was generally insignificant inflammation. These features are similar if not identical to lichen simplex chronicus of the skin, a benign condition caused by chronic irritation. Ten randomly selected cases were immunostained for p16INK4A(p16), a tumor suppressor protein expressed in dysplastic epithelium. All lesions were negative for p16. Benign alveolar ridge keratosis is a specific clinicopathologic entity that should be removed from the category of leukoplakia as is currently the practice for clinical white lesions with a specific, consistently recognizable histologic appearance.