title: Primary Ewing sarcoma of the spine mimicking a psoas abscess secondary to spinal infection.
abstract: METHODS
  A case of primary Ewing sarcoma of the lumbar spine is presented.
  
  
  OBJECTIVE
  To present and review a rare case of primary Ewing sarcoma of the lumbar spine that required differentiation from spinal infection.
  
  
  BACKGROUND
  Primary Ewing sarcoma originating from the spinal column is very rare. Because Ewing sarcoma is one of the most aggressive bone tumors with high proliferative and invasive potential, its clinical symptoms and variety of imaging manifestations can mimic the pathologic findings of other diseases, including infectious diseases.
  
  
  METHODS
  The clinical course, radiologic features, pathology and treatment outcome of a patient with primary Ewing sarcoma of the lumbar spine was documented.
  
  
  RESULTS
  The magnetic resonance imaging findings showed an abnormal marrow signal at the L2 vertebra and significant enlargement of the unilateral iliopsoas muscle. Immunologic and molecular analysis of the surgical specimen provided a diagnosis of Ewing sarcoma. Laminotomy followed by multidisciplinary therapy including chemotherapy and radiation therapy was effective for treating this case.
  
  
  CONCLUSIONS
  We report a case of Ewing sarcoma that mimicked a psoas abscess secondary to spinal infection. Abnormal magnetic resonance imaging images, as well as a confusing clinical course, made diagnosis difficult. When enlargement of the iliopsoas with a vertebral lesion is detected in a child with low back pain, Ewing sarcoma should be included in the differential diagnosis.
authors.affiliation: Department of Orthopaedic Surgery, Mie University Graduate School of Medicine, Mie, Japan. k_akeda@clin.medic.mie-u.ac.jp
authors.forename: Koji
authors.initials: K
authors.lastname: Akeda
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Kasai
authors.forename: Eiji
authors.initials: E
authors.lastname: Kawakita
authors.forename: Masashi
authors.initials: M
authors.lastname: Seto
authors.forename: Toshibumi
authors.initials: T
authors.lastname: Kono
authors.forename: Atsumasa
authors.initials: A
authors.lastname: Uchida
mesh_terms: D002648:Child; D003937:Diagnosis, Differential; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D016659:Psoas Abscess / Q000175:diagnosis* / Q000209:etiology; D012512:Sarcoma, Ewing / Q000175:diagnosis*; D013122:Spinal Diseases / Q000150:complications / Q000175:diagnosis*; D013125:Spinal Neoplasms / Q000175:diagnosis*