title: Pericytosis and edema generation: a unique clinicopathological variant of meningioma.
abstract: OBJECTIVE
  We report a group of eight patients with a distinctive histological variant of meningioma that is associated with severe peritumoral edema. The clinical presentation, radiographic findings, and histology of this type of tumor may lead to misdiagnosis as an aggressive or malignant process.
  
  
  METHODS
  We reviewed the histology from patients who had removal of meningiomas performed in our institution between 1978 and 1992. Tumors having abnormal proliferation of cells in the intramural vascular spaces were selected for study; case histories and radiographs were reviewed. Tumor material was subjected to special stains, immunocytochemical examination, and election microscopy.
  
  
  RESULTS
  Several lesions were misread radiographically as being malignant. Patients underwent craniotomy with complete excision of the tumor. All lesions were small (< or = 3 cm), and no brain invasion, unusual tumor vascularity, or dural sinus involvement was noted in any case. Histologically, the meningioma pattern in each case was meningothelial and benign in appearance. The immunocytochemical and electron microscopic features of the unusual cells in the blood vessel walls are most consistent with their being of pericytic origin. All patients have remained asymptomatic and without evidence of tumor recurrence with follow-up from 3 to 12 years.
  
  
  CONCLUSIONS
  These tumors showed proliferation of pericytes in blood vessel walls and represent a new subtype of meningothelial meningioma. The apparently benign nature of these lesions necessitates their recognition. Characteristic findings of pericytic proliferation associated with edema generation have led us to descriptively term this the PEG variant of meningioma.
authors.affiliation: Department of Neurosurgery, Wake Forest University, Bowman Gray School of Medicine, Winston-Salem, North Carolina, USA.
authors.forename: J C
authors.initials: JC
authors.lastname: Robinson
authors.forename: V R
authors.initials: VR
authors.lastname: Challa
authors.forename: D S
authors.initials: DS
authors.lastname: Jones
authors.forename: D L
authors.initials: DL
authors.lastname: Kelly
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis; D001812:Blood-Brain Barrier / Q000502:physiology*; D001921:Brain / Q000098:blood supply / Q000473:pathology; D001929:Brain Edema / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D002455:Cell Division / Q000502:physiology*; D003399:Craniotomy; D003937:Diagnosis, Differential; D005260:Female; D006393:Hemangiopericytoma / Q000098:blood supply / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D006801:Humans; D008297:Male; D008577:Meningeal Neoplasms / Q000098:blood supply / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D008579:Meningioma / Q000098:blood supply / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D008854:Microscopy, Electron; D008875:Middle Aged; D009131:Muscle, Smooth, Vascular / Q000473:pathology*; D014057:Tomography, X-Ray Computed
chemical_list: D014408:Biomarkers, Tumor