Alveolar ridge keratosis: a clinicopathologic entity

Abstract

Alveolar ridge keratosis (ARK) is a common benign white papule or plaque that occurs on the keratinized gingiva of the maxillary or mandibular alveolar ridge with characteristic histologic features. This is a retrospective study of 70 consecutive cases of ARK accessioned over a 26-month period. Detailed information was available on 27 cases through a mail-in questionnaire. The male:female ratio was 3.6:1. The retromolar pad was involved in 69% of cases, with 30% of such cases being bilateral. All lesions were less than 2 cm in greatest dimension. A tobacco habit was noted in 50% of cases. Histologically, the lesions were characterized by moderate to marked hyperorthokeratosis, with wedge-shaped hypergranulosis, slight surface papillomatosis, acanthosis in the form of long tapered rete ridges, and no to mild inflammatory cell infiltration. These features are similar if not identical to what is reported as lichen simplex chronicus of the skin, a benign condition caused by chronic irritation. Ten cases were stained immunohistochemically for p16INK4A(p16) a tumor suppressor protein commonly expressed in oral intraepithelial neoplasia grade II and III, carcinoma-in-situ, and invasive fronts of squamous cell carcinomas. All lesions were negative for p16, demonstrating the benign nature of the lesion. All the cases that were excised (17/27) did not recur. None developed malignancy at the site. ARK is a specific clinicopathologic entity that should be removed from the category of leukoplakia and placed in its own category, as is currently the practice for clinical white lesions with a specific well recognized histologic pattern, such as lichen planus and morsicatio buccarum.