1. ¹Clinical Genetics Department, Federal University of Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil
2. ²Department of Microbiology and Immunology, Teres|[oacute]|polis Medical School, Teres|[oacute]|polis, Rio de Janeiro, Brazil
3. ³Institute of Health Sciences, Veiga de Almeida University, Rio de Janeiro, Brazil
4. ⁴Neurology Department, Massachusetts General Hospital, MA

Abstract

Introduction: An observational, descriptive case study was performed at the Servi|[ccedil]|o de Gen|[eacute]|tica Cl|[iacute]|nica do Instituto de Puericultura e Pediatria Martag|[atilde]|o Gesteira of the Federal University of Rio de Janeiro, Brazil, on patients with neurofibromatosis type 1 (NF1). The serum IgE levels of 75 patients presenting neurofibromas, plexiform neurofibromas, or neurofibromatosis with no neurofibromas, were described and compared. We also determined the expression of the p53 protein in the neurofibromas and plexiform neurofibromas of 50 of the patients with NF1.

Objectives: To describe and compare serum IgE levels in NF1 patients. To describe and compare the expression of the tumor suppressor p53 protein in the NF1 patients with neurofibromas and plexiform neurofibromas. To observe if there is any correlation between serum IgE levels and the size of the neurofibromas in NF1 patients.

Materials and Methods: To determine serum IgE levels in all of the patients, we used the Phadebas IgE RIST (Radioimmunosorbent Test) on previously collected serum samples from 75 NF1 patients. To determine the levels of p53 protein, immunohistochemistry was performed on previously obtained samples from the 50 patients with neurofibromas and plexiform neurofibromas.

Results: Two patients were identified with p53 mutation, both of which presented plexiform neurofibromas. Both of these patients also presented elevated serum IgE levels (>502 IU/ml). In the male patients with neurofibromas and plexiform neurofibromas, we observed a trend of an increase in pedunculated neurofibroma size correlated with elevated IgE levels. In the patient group presenting plexiform neurofibromas, we observed a trend of increase in cutaneous and subcutaneous neurofibroma size correlated with increased serum IgE levels.

Conclusion: The two patients who presented p53 mutation, indicated by high levels of the protein in the plexiform neurofibromas, later showed signs of malignant transformation and underwent surgeries. This finding may indicate that at the time of the biopsy, malignant transformation had begun, or that, in the case of plexiform neurofibromas, positive testing for p53 mutation could be an indicator of future malignant transformation. Based on our results, there appears to be a correlation between increase in neurofibroma size and serum IgE elevation in NF1 patients in Brazil.