Immunohistochemical detection of nerve growth factor (NGF) in follicular and plexiform ameloblastoma - A novel study

Background: Ameloblastoma is the second most common odontogenic tumor that holds a unique position among benign tumors due to its locally destructive and invasive nature. The differed tumor biology behind follicular and plexiform ameloblastoma is always an enigma. Nerve growth factor (NGF), a neurotrophin that plays a major role during odontogenesis, could also possibly play a role in the pathogenesis of odontogenic tumors such as ameloblastoma. With this background, the study was aimed to investigate the expression of NGF in follicular and plexiform ameloblastoma. Objectives: The objectives of this study were to analyze the immunohistochemical expression pattern of NGF in ameloblastoma and to compare the immunohistochemical expression pattern of NGF among the follicular and plexiform histological types of ameloblastoma. Materials and Methods: Forty histological sections of ameloblastomas (20 follicular and 20 plexiform) were stained immunohistochemically with anti-human NGF mouse IgG monoclonal antibody and the staining was analyzed statistically. Results: Almost all the 40 ameloblastoma samples (20 follicular and 20 plexiform) showed positive immunoreactivity to NGF. Both peripheral pre-ameloblast-like tall columnar cells and central stellate-reticulum-like cells showed positive reactivity. The pattern of staining was membranous in the immunoreactive cells. The chi 2 value for the immunoexpression between follicular and plexiform ameloblastoma was statistically significant with a P value <0.002. A possible mechanism has been proposed after studying the results with the downstream pathways obtained from literature. Conclusion: The pattern of expression of NGF is seen in both follicular and plexiform ameloblastoma. But the intensity is more in plexiform than that of follicular ameloblastoma.