title: Phenotypic diversity of neurofibromatosis 2: association with plexiform schwannoma.
abstract: OBJECTIVE
  Plexiform schwannoma (PS) is a rare variant of benign schwannoma characterized by a multinodular and plexiform growth pattern. In contrast to plexiform neurofibroma. PS is not associated with neurofibromatosis 1 (NF-1; von Recklinghausen's disease) and has no propensity for malignant transformation. The purpose of this study was to clarify the relationship between PS and the entities of neurofibromatosis 2 (NF-2; bilateral acoustic neurofibromatosis) and schwannomatosis.
  
  
  RESULTS
  Six cases of PS associated with NF-2 or meningioma were retrospectively studied clinicopathologically and immunohistochemically. Four cases of PS were found among the patients with NF-2, and all of these had multiple PSs; three cases also had multiple schwannomas of the spinal nerve roots and two of these had meningioma. Two other patients had meningioma, but not NF-2. Four patients were male and two were female. The ages ranged from 18 to 52 years (mean 29.6 years). Histologically, PS showed the histological features that have been previously described, i.e. schwannoma composed of a predominant Antoni A-type component with a plexiform growth pattern. Immunohistochemically, the tumour cells were positive for S100 protein. Each nodule was surrounded by perineural cells which were positive for epithelial membrane antigen.
  
  
  CONCLUSIONS
  It is important to recognize that PS could be associated with NF-2 or meningioma. The combination of PS and meningioma may be a 'formes frustes' of NF-2, and is clinically overlapped with schwannomatosis.
authors.affiliation: Department of Pathology, Faculty of Medicine, University of Tokyo, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Ishida
authors.forename: M
authors.initials: M
authors.lastname: Kuroda
authors.forename: T
authors.initials: T
authors.lastname: Motoi
authors.forename: T
authors.initials: T
authors.lastname: Oka
authors.forename: T
authors.initials: T
authors.lastname: Imamura
authors.forename: R
authors.initials: R
authors.lastname: Machinami
mesh_terms: D000293:Adolescent; D000328:Adult; D016543:Central Nervous System Neoplasms / Q000378:metabolism / Q000473:pathology; D005260:Female; D016515:Genes, Neurofibromatosis 2; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008579:Meningioma / Q000378:metabolism / Q000473:pathology; D008875:Middle Aged; D009442:Neurilemmoma / Q000473:pathology*; D016518:Neurofibromatosis 2 / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D010524:Peripheral Nervous System Neoplasms / Q000378:metabolism / Q000473:pathology; D010641:Phenotype; D009418:S100 Proteins / Q000378:metabolism
chemical_list: D009418:S100 Proteins