The blue nevus: a rare lesion of the oral cavity

Melanocytic nevi are the most common benign proliferations of melanin-producing cells in Caucasians; up to 30 lesions can be seen in an adult individual. Lesional cells are usually superficially located in the epidermis-superficial dermis. Blue nevi are less common. They represent benign proliferations of fusiform dermal melanocytes in the submucosa or deep dermis. These cells contain abundant melanin granules. The blue color is due to the deep location of the lesional cells and the Tyndall effect. In the oral cavity, both melanocytic and blue nevi are rare; the hard palate being the site of predilection. The risk of malignant transformation of blue nevi is unknown; this is mainly due to the rarity of reported oral lesions. Therefore, the reporting of such cases is key to a better understanding and possibly predicting the clinical behavior of intraoral blue nevi. This article presents 2 patients with blue nevi in the oral cavity, and reviews the differential diagnosis of solitary pigmented lesions, including oral melanoma. The importance of proper diagnosis and treatment of oral pigmentations in general, and of melanocytic nevi in particular, is underlined in order to help the general dentist manage patients presenting with such lesions.