Original ArticlesHybrid Neurofibroma/Schwannoma is Overrepresented Among Schwannomatosis and Neurofibromatosis PatientsHarder, Anja MD*; Wesemann, Martin*; Hagel, Christian MD†; Schittenhelm, Jens MD‡; Fischer, Susan*; Tatagiba, Marcos MD§; Nagel, Christoph MD§; Jeibmann, Astrid MD*; Bohring, Axel MD∥; Mautner, Victor-Felix MD¶; Paulus, Werner MD*Author Information *Institute of Neuropathology ∥Institute of Human Genetics, University Hospital Münster, Münster, Germany †Institute of Neuropathology ¶Department of Neurology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany ‡Department of Neuropathology, Institute of Pathology and Neuropathology §Department of Neurosurgery, University of Tübingen, Tübingen, Germany Conflicts of Interest and Source of Funding: Supported by “Innovative Medical Research,” University of Münster Medical School (HA121006). No funding was received for this work from the National Institutes of Health; Wellcome Trust and Howard Hughes Medical Institute. Correspondence: Anja Harder, MD, Institute of Neuropathology, University Hospital Münster, Albert-Schweitzer-Campus 1, Building A7, 48149 Münster, Germany (e-mail: [email protected]). The American Journal of Surgical Pathology: May 2012 - Volume 36 - Issue 5 - p 702-709 doi: 10.1097/PAS.0b013e31824d3155 Buy Metrics Abstract We analyzed the histologic features of peripheral nerve sheath tumors occurring in 14 patients with schwannomatosis. Among a total of 31 tumors, 19 tumors (61%) showed schwannoma-like nodules within a neurofibroma-like tumor, corresponding to hybrid neurofibroma/schwannoma. At least 1 hybrid tumor occurred in 10 of 14 (71%) schwannomatosis patients. We then retrieved cases of hybrid tumors without documented relation to schwannomatosis from our database and identified 41 tumors arising in 23 patients. More than half of these patients (14/23) were reported to suffer from multiple peripheral nerve sheath tumors, favoring a tumor syndrome. Indeed, analysis of clinical records revealed the diagnosis of neurofibromatosis type 2 (NF2) in 26% (6/23), neurofibromatosis type 1 (NF1) in 9% (2/23), definite schwannomatosis in 4% (1/23), and possible schwannomatosis in 13% (3/23) of patients with multiple nerve sheath tumors. Our findings suggest that hybrid neurofibroma/schwannoma represents a common tumor type in schwannomatosis and shows a striking association with neurofibromatoses. © 2012 Lippincott Williams & Wilkins, Inc.