Hybrid peripheral nerve sheath tumors

Purpose: The aim of this study was to evaluate patients formerly diagnosed as neurofibroma and schwannoma in terms of hybrid peripheral nerve sheath tumors (PNSTs) via histopathological and immunohistochemical analysis Materials and Methods: Of 115 patients formerly diagnosed as neurofibroma or schwannoma, have mixed morphology consistent with suspected hybrid PNST on histopathological re-assessment were included in this retrospective study. Immunohistochemically, S100, CD34 and EMA were performed to patients of suspected hybrid PNST. Results:Suspected hybrid PNST was considered in 32 (27.8%) of 115 cases based on histopathological re-assessment, while the definite diagnosis of hybrid PNST was considered in 22 (19.1%) cases based on immunohistochemical staining, including schwannoma-neurofibroma and schwannoma-perineurioma in 18 (81.8%) and 4 (18.2%) patients, respectively. Conclusion: Hybrid PNSTs are usually benign and have distinct histopathologic and immunohistochemistry findings. ？n the literature rare case reports have described local recurrence and malignant transformation in hybrid PNSTs. Therefore, further studies are needed to demonstrate the pathogenetic and prognostic significance of these tumors. Because of the risk of recurrence and malignancy potential, this tumors should be kept in mind when the diagnosis of peripheral nerve sheath tumor