Expression of S-100, EMA, CD34 and presence of mast cells in eight oral neurofibromas, and a review of 127 cases of the literature

INTRODUCTION: The rarity of oral neurofibromas (ONs) generates problems regarding their epidemiological and immunohistochemical characterization. OBJECTIVES: The aim of this study was to evaluate the expression of different markers in ONs and review epidemiologic data reported in the literature. MATERIAL AND METHODS: Clinicopathologic, immunohistochemical (markers S-100, epithelial membrane antigen [EMA], CD34) and histochemical (modified-Ziehl-Neelsen-method) studies were performed in eight cases of ON diagnosed in the Department of Pathology and Legal Medicine (DPML), Universidade Federal do Ceará (UFC), Ceará, Brazil, between 1994 and 2010. RESULTS: Oral neurofibromas represented 0.2% of the oral lesions diagnosed by our service in 16 years, and the buccal mucosa was the most frequent oral site (71.4%). Seven (87.5%) and 8 (100.0%) cases were positive for S-100 and CD34, respectively, and none for EMA. Mast cells were identified in seven cases (87.5%). The literature search indicated that solitary ONs are more common and occur preferentially in females, affecting patients between 30 and 40 years old. The alveolar ridge is the most commonly involved site. CONCLUSION: S-100- and CD34 markers proved to be of great value as a diagnostic tool, unlike EMA staining. Identification of mast cells in most cases suggests their involvement in this tumor pathogenesis. The clinicopathologic data retrieved from the literature enabled the establishment of a more consistent epidemiological profile.