title: Cystic schwannoma of the maxillary sinus.
abstract: OBJECTIVE
  Although 25-45% of all schwannomas are reported to occur in the head and neck region, nasal cavity and paranasal sinus involvement is rare, with 32 such cases described till 1999. Of these cases, only three were cystic. Herein we present a cystic schwannoma of the maxillary sinus of a 66-year-old, otherwise healthy male patient.
  
  
  METHODS
  The tumor tissue was routinely processed, embedded in paraffin, and stained with H&E. Immunostaining was performed for S-100 protein, epithelial membrane antigen (EMA) and cytokeratin.
  
  
  RESULTS
  A mass with sudden enlargement, inhomogeneous enhancement with cystic areas, S-100 positive membrane-like structures lining the cystic cavity of an otherwise classical schwannoma were the main features encountered in our case.
  
  
  CONCLUSIONS
  We recommend that cystic schwannoma should be kept in mind in the differential diagnosis of cystic masses of the maxilla.
authors.affiliation: Department of Pathology, School of Medicine, Dokuz Eylül University, 35340 Inciralti/Izmir, Turkey. sulen.sarioglu@deu.edu.tr
authors.forename: Sülen
authors.initials: S
authors.lastname: Sarioğlu
authors.forename: Sermin
authors.initials: S
authors.lastname: Ozkal
authors.forename: Ataman
authors.initials: A
authors.lastname: Güneri
authors.forename: Emel
authors.initials: E
authors.lastname: Ada
authors.forename: Banu
authors.initials: B
authors.lastname: Sis
authors.forename: Taner Kemal
authors.initials: TK
authors.lastname: Erdağ
authors.forename: H Uğur
authors.initials: HU
authors.lastname: Pabuççuoğlu
mesh_terms: D000368:Aged; D014408:Biomarkers, Tumor / Q000032:analysis; D003560:Cysts / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D003937:Diagnosis, Differential; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008443:Maxillary Sinus / Q000473:pathology / Q000601:surgery; D008444:Maxillary Sinus Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D009442:Neurilemmoma / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D009418:S100 Proteins / Q000032:analysis; D014057:Tomography, X-Ray Computed
chemical_list: D014408:Biomarkers, Tumor; D009418:S100 Proteins