Oral neurovascular hamartoma: A lesion searching for a name

Background: Neurovascular hamartoma (NVH), in particular in the oral cavity, is rarely described in the literature. The low number of cases may reflect a genuine rarity of the lesion, or it may be due to its being unrecognized and/or under-reported. Objectives: To investigate clinical and microscopic features of oral NVH and to define microscopic diagnostic criteria with emphasis on the differential diagnosis. Methods: Archival cases diagnosed as oral NVH between 1999 and 2011 were retrieved; clinical and demographic data were collected, and a paired morphometric analysis was conducted, with each case of NVH a case of fibrous hyperplasia (FH) from the same oral location. The nerve bundle and blood vessel density were quantified in five microscopic fields at ×100 magnification. Results: The study group included 25 oral NVH, 11 men and 14 women, aged 6-76years, (mean 44). The majority occurred in the tongue (54%), followed by the buccal mucosa and lower lip (17% each), clinically presenting as asymptomatic 0.25-2.5cm exophytic masses. Microscopic characteristics included poorly circumscribed masses of closely packed nerve bundles and blood vessels in a loose matrix, containing minimal or no inflammation. The mean nerve bundle density was significantly higher in NVH (4.28±1.26) in comparison with FH (0.27±0.27), (P<0.00001), and mean vessel density was significantly lower (5.98±1.4 vs. 7.8±1.9, respectively), (P<0.0003). Conclusion: Oral NVH may not be as rare as previously considered. Morphometric analysis demonstrated that NVH presents a separate distinct entity.