title: [CT and MRI imaging features of peripheral primitive neuroectodermal tumors].
abstract: OBJECTIVE
  To investigate the CT and MRI features of peripheral primitive neuroectodermal tumors (pPNETs) and evaluate its diagnostic value.
  
  
  METHODS
  The clinicopathological data of 9 surgically treated patients with peripheral primitive neuroectodermal tumors confirmed by pathology were collected, spiral CT (4/9) and MRI (6/9) plain scanning and dynamic enhancement scanning were performed preoperatively. Both CT and MRI scannings were performed in 1 case. Those CT and MR images were retrospectively reviewed and analyzed together with clinicopathological findings.
  
  
  RESULTS
  The 9 lesions were located in skeletal muscles (n = 6), pelvic cavity (n = 2) and thoracic cavity (n = 1). The tumor size was 7.4-18.3 cm in diameter with a mean diameter of 11.6 cm. The shape of those lesions was round or ellipse (4 lesions) and irregular (5 lesions). The tumor usually presented as ill-defined masses, with homogeneous (n = 2) or inhomogeneous density (n = 7). Seven cases, including the 3 lesions located in the chest and pelvis, showed obvious necrosis and multilocular cyst formation. The tumors showed iso-density as that of the adjacent muscles on CT plain scans and moderate heterogeneous enhancement after intravenous injection of contrast agents. The features of the tumors on the MRI including slightly low signal intensity on SE T1-weighted imaging, iso-signal intensity or slightly high signal intensity on FSE T2-weighted imaging and heterogeneous dynamic delayed contrast-enhancement with obvious necrosis in most of them. Six cases had a lesion in the skeletal muscles, presented as a giant ill-defined masse surrounding bone and extended along neural route with bone destruction to varying degrees.
  
  
  CONCLUSIONS
  Primitive neuroectodermal tumor is a kind of malignant tumor with proliferation of small, undifferentiated neuroectodermal cells, usually occurring in children or adolescent and frequently located in the extremities, chest cavity, pelvic cavity and chest wall. It typically presents as a large, ill-defined masse extending along neural route with heterogeneous and obvious enhancement after intravenous injection of contrast agents. The tumors located in the chest and pelvic cavities and some in the extremities show obvious necrosis and multilocular cyst formation, while some of the tumors in the extremities appear as homogeneous solid masses.
authors.affiliation: Department of Diagnostic Radiology, Zhongshan Hospital, Fudan University, Shanghai, China. zhou.jianjun@zs-hospital.sh.cn
authors.forename: Jian-jun
authors.initials: JJ
authors.lastname: Zhou
authors.forename: Jian-hua
authors.initials: JH
authors.lastname: Wang
authors.forename: Meng-su
authors.initials: MS
authors.lastname: Zeng
authors.forename: Fu-hua
authors.initials: FH
authors.lastname: Yan
authors.forename: Kang-rong
authors.initials: KR
authors.lastname: Zhou
authors.forename: Jian-guo
authors.initials: JG
authors.lastname: Ding
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D003951:Diagnostic Errors; D005260:Female; D051677:Histiocytoma, Malignant Fibrous / Q000175:diagnosis; D006801:Humans; D008297:Male; D019042:Muscle Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D018482:Muscle, Skeletal; D018241:Neuroectodermal Tumors, Primitive, Peripheral / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D010386:Pelvic Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D011859:Radiography; D012189:Retrospective Studies; D013899:Thoracic Neoplasms / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000473:pathology; D055815:Young Adult