title: Primitive neuroectodermal tumor of the orbit in adults: a case series.
abstract: OBJECTIVE
  To present the clinical, radiologic, and histopathologic features of orbital primitive neuroectodermal tumor (PNET) in 5 adult patients.
  
  
  METHODS
  Retrospective case series of 5 adult patients with orbital PNET. Orbitotomy was performed in all cases. The authors report clinical findings, radiologic features, histopathology, immunohistochemical analysis, management, and outcomes for 5 patients with orbital PNET.
  
  
  RESULTS
  Five adult patients presented with progressive unilateral proptosis and visual impairment. Common radiographic findings included a heterogeneous mass without associated destructive features, located in the superior and/or lateral orbit. Four cases demonstrated strong immunohistochemical staining for CD99 in a membranous pattern. One case required chromosomal analysis with fluorescence in situ hybridization to confirm the diagnosis. All patients received chemotherapy and/or orbital radiation with resolution of proptosis but no improvement of vision. One patient died of disease.
  
  
  CONCLUSIONS
  To the authors' knowledge, this is the largest series of orbital PNET in adults. This tumor has an age demographic wider than previously believed and should be considered in the differential diagnosis of a hypercellular small round cell orbital tumor in both children and adults. Current treatment regimens are not standardized but typically use a similar approach to the treatment of Ewing sarcoma. Orbital PNET appears to have less propensity for metastasis compared with PNET in other locations. However, long-term aggressiveness remains to be proven.
authors.affiliation: Department of Ophthalmology, Division of Ophthalmic Plastic and Reconstructive Surgery, University of California at San Diego, La Jolla, California 92093-0946, U.S.A.
authors.forename: Weerawan
authors.initials: W
authors.lastname: Chokthaweesak
authors.forename: Christine C
authors.initials: CC
authors.lastname: Annunziata
authors.forename: Oday
authors.initials: O
authors.lastname: Alsheikh
authors.forename: John D
authors.initials: JD
authors.lastname: Ng
authors.forename: David J
authors.initials: DJ
authors.lastname: Wilson
authors.forename: Atiya
authors.initials: A
authors.lastname: Mansoor
authors.forename: Vassil
authors.initials: V
authors.lastname: Kaimatchiev
authors.forename: Robert
authors.initials: R
authors.lastname: Weatherhead
authors.forename: Jack
authors.initials: J
authors.lastname: Rootman
authors.forename: Geva
authors.initials: G
authors.lastname: Mannor
authors.forename: Kanjana
authors.initials: K
authors.lastname: Leelapatranurak
authors.forename: Bobby S
authors.initials: BS
authors.lastname: Korn
authors.forename: Don O
authors.initials: DO
authors.lastname: Kikkawa
mesh_terms: D000071443:12E7 Antigen; D000368:Aged; D015703:Antigens, CD / Q000032:analysis; D014408:Biomarkers, Tumor / Q000032:analysis; D015815:Cell Adhesion Molecules / Q000032:analysis; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D018241:Neuroectodermal Tumors, Primitive, Peripheral / Q000737:chemistry / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D013508:Ophthalmologic Surgical Procedures; D009918:Orbital Neoplasms / Q000737:chemistry / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D011859:Radiography
chemical_list: D000071443:12E7 Antigen; D015703:Antigens, CD; D014408:Biomarkers, Tumor; C061828:CD99 protein, human; D015815:Cell Adhesion Molecules