Melanocytic nevi of the oral mucosa - no evidence of increased risk for oral malignant melanoma: an analysis of 119 cases.

Pigmented nevi of the oral mucosa are rare benign melanocytic tumours. Epidemiological data are scanty, and the etiology and pathogenesis of these lesions are poorly understood. Reports are mainly based on isolated cases or a relatively small series of cases. Some reviews have drawn attention to the frequent localization of these lesions on the hard palate, the site of preference for oral malignant melanoma (OMM). However, as yet, there is no direct proof that oral melanocytic nevi (OMNs) constitute precursor lesions of OMM. 119 cases of OMNs, registered at the nationwide Registry of Pathology (PALGA) in The Netherlands during the period 1980-2005, have been evaluated. Subepithelial OMNs were the most commonly recorded lesions (96 cases), followed by blue (10 cases), compound (7 cases) and junctional OMNs (5 cases). Only one case of a combined nevus was recorded. None of the patients developed OMM during a mean follow-up period of 8.6years. We present an analysis of this series of cases, together with a review of the literature. The findings of the present evaluation do not give support for the hypothesis of OMN being a marker for an increased risk of future development of OMM.