Clinicopathologic and immunohistochemical features of oral neurofibroma

Objective: The purposes of this study were to assess clinical, histopathological and immunohistochemical features of 22 oral neurofibromas (NFs) and discuss with previously described literature, addressing the main aspects regarding the differential diagnosis. Materials and methods: Immunohistochemical reactions included S-100, CD34, GLUT-1, EMA, Ki-67, p53 and Collagen IV and histochemical reactions for Alcian blue. Results: Clinically, the preferential location was the maxillary bones, tongue and buccal mucosa. Microscopically, widely spread spindle-shaped cells with scant cytoplasm and elongated nuclei were observed. Immunostaining revealed that the tumor cells weakly expressed GLUT-1, Collagen IV, Ki-67 and p53. They were variably positive for CD34, S-100 protein and membrane epithelial antigen (EMA). Conclusions: The different types of nerve sheath cells observed in the present series reinforce the presence of heterogeneous population in NFs. The strong positivity for S-100 suggests that the lesions were more composed by S-100-positive Schwann cells than other cells. Besides, the high number of CD34-positive cells suggests that this marker can be useful for the differential diagnosis of NFs against PEN, traumatic neuromas and Schwannomas. Finally, the low immunostaining for p53 and Ki-67 may indicate that NFs massively composed by S-100-positive Schwann cells present low potential of aggressiveness and malignant transformation.