title: Intraneural perineurioma: a systematic review with illustrative cases.
abstract: BACKGROUND
  Intraneural perineurioma may be confused with other "onion bulb" Schwann cell entities (localized hypertrophic neuropathy, reactive/demyelinating processes, or inherited polyneuropathies of Charcot-Marie-Tooth/Dejerine Sottas) due to similar clinical, radiologic, and histologic features. Perineurial and Schwann cells can only be differentiated by ultrastructure and immunohistochemsitry.
  
  
  OBJECTIVE
  To identify and summarize the clinicopathologic features of true cases of intraneural perineurioma from the English language literature.
  
  
  METHODS
  A systematic review was performed on definitive intraneural perineuriomas identified through Medline. Baylor College of Medicine-affiliated hospitals' anatomic pathology databases yielded 2 illustrative intraneural perineurioma cases.
  
  
  METHODS
  Intraneural perineurioma inclusion criteria consisted of characteristic histology and confirmation of perineurial cell lineage by either immunohistochemistry (epithelial membrane antigen positive, S100 protein negative) and/or ultrastructural analysis (thin cytoplasmic processes with an incomplete basal lamina, poorly formed tight junctions, and pinocytotic vesicles).
  
  
  METHODS
  Clinicopathologic data were extracted from all identified articles, with subsequent statistical analysis of the following parameters: age, sex, race, tumor location, tumor size, duration of symptoms prior to diagnosis, treatment modalities and outcomes measures, follow-up assessment for tumor recurrence and metastasis, clinical features (history of trauma, motor/sensory abnormalities, clinical/family history), and diagnostic workup (routine histology, immunohistochemistry, ultrastructural analysis, and molecular/cytogenetic characteristics).
  
  
  CONCLUSIONS
  Intraneural perineurioma is a neoplastic proliferation of perineurial cells with unique immunohistochemistry and ultrastructural features, and it is distinct from other onion bulb Schwann cell-derived entities. Despite harboring molecular abnormalities of the long arm of chromosome 22, intraneural perineurioma has not been associated with neurofibromatosis. Intraneural perineurioma is a benign peripheral nerve sheath tumor that does not recur or metastasize.
authors.affiliation: Department of Clinical Pathology, William Beaumont Hospital, 3601 W Thirteen Mile Rd, Royal Oak, MI 48073, USA. bobby.boyanton@beaumont.edu
authors.forename: Bobby L
authors.initials: BL
authors.lastname: Boyanton
authors.forename: John K
authors.initials: JK
authors.lastname: Jones
authors.forename: Saleh M
authors.initials: SM
authors.lastname: Shenaq
authors.forename: M John
authors.initials: MJ
authors.lastname: Hicks
authors.forename: Meenakshi B
authors.initials: MB
authors.lastname: Bhattacharjee
mesh_terms: D002454:Cell Differentiation; D049109:Cell Proliferation; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D018396:Mucin-1 / Q000378:metabolism; D018317:Nerve Sheath Neoplasms / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology*; D009423:Nervous System Neoplasms / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology*; D014059:Tongue / Q000294:innervation; D014459:Ulnar Nerve / Q000473:pathology