Immunolocalization of erythropoietin and erythropoietin receptor in vestibular schwannoma.

Vestibular schwannomas constitute approximately 6% of intracranial tumors. Apart from the association with neurofibromatosis-2 (NF-2), where a defect in chromosome 22 has been identified, the pathogenesis of sporadic vestibular schwannomas is largely unknown. Very few studies have explored the role of neurotrophic growth factors in vestibular schwannoma. The objective of this study is to evaluate for the presence and pattern of EPO and EPO-R expression within vestibular schwannomas. Our hypothesis that erythropoietin (EPO) and erythropoietin receptor (EPO-R) were expressed in vestibular schwannomas was based on a recent report of rapid growth of a vestibular schwannoma in a patient undergoing preoperative EPO treatment. Using immunohistochemistry, we have demonstrated that both EPO and EPO-R are expressed in a majority of these tumors.