title: Imaging features of alveolar soft-part sarcoma: a report from Children's Oncology Group Study ARST0332.
abstract: OBJECTIVE
  There are few studies in the literature regarding the imaging features of alveolar soft-part sarcoma (ASPS). We performed a comprehensive assessment of the imaging characteristics of this rare tumor to determine whether there are features that suggest the diagnosis.
  
  
  METHODS
  Twenty-two subjects with ASPS underwent pretherapy imaging as part of enrollment in Children's Oncology Group protocol ARST0332 for the treatment of nonrhabdomyosarcoma soft-tissue sarcomas: 16 patients underwent MRI; three, CT; and three, both MRI and CT. Two radiologists retrospectively reviewed the imaging studies by consensus and recorded tumor location, size, contour, internal architecture, signal characteristics, presence of flow voids, and enhancement patterns.
  
  
  RESULTS
  The 12 females and 10 males in the study group ranged in age from 8 to 23 years 7 months (mean, 15 years 8 months). The most common anatomic site was the lower extremity (12/22, 55%) followed by the upper extremity (4/22, 18%). The maximal tumor diameter ranged from 2.3 to 20.0 cm (median, 5.9 cm). All tumors imaged with MRI had flow voids (19/19, 100%), and 19 (19/22, 86%) had large peripheral vessels, lobulated margins, and nodular internal architecture. Unenhanced T1-weighted MRI was available for 18 tumors: 14 (14/18, 78%) appeared slightly hyperintense to muscle. Of the 16 tumors imaged with contrast material, 11 (11/16, 69%) showed intense enhancement and five (5/16, 31%), moderate enhancement. Six tumors (6/16, 38%) had a thick enhancing peripheral rim with a nonenhancing center consistent with necrosis.
  
  
  CONCLUSIONS
  The imaging features of ASPS include flow voids, large peripheral vessels, internal nodularity, and lobulated margins. Contrast administration produces intense to moderate enhancement, sometimes with a thick enhancing peripheral rim around central necrosis. Extremity tumors with these imaging features in a child or young adult should suggest the diagnosis of ASPS.
authors.affiliation: 1 Department of Radiological Sciences, St. Jude Children's Research Hospital, 262 Danny Thomas Pl, MS 220, Memphis, TN 38105.
authors.forename: M Beth
authors.initials: MB
authors.lastname: McCarville
authors.forename: Sofia
authors.initials: S
authors.lastname: Muzzafar
authors.forename: Simon C
authors.initials: SC
authors.lastname: Kao
authors.forename: Cheryl M
authors.initials: CM
authors.lastname: Coffin
authors.forename: David M
authors.initials: DM
authors.lastname: Parham
authors.forename: James R
authors.initials: JR
authors.lastname: Anderson
authors.forename: Sheri L
authors.initials: SL
authors.lastname: Spunt
mesh_terms: D000293:Adolescent; D001132:Arm; D002648:Child; D005260:Female; D006801:Humans; D007866:Leg; D008279:Magnetic Resonance Imaging; D008297:Male; D019042:Muscle Neoplasms / Q000175:diagnosis*; D015203:Reproducibility of Results; D018234:Sarcoma, Alveolar Soft Part / Q000175:diagnosis* / Q000473:pathology; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: Children's Oncology Group Study ARST0332; alveolar soft-part sarcoma (ASPS); imaging