title: Differential diagnosis between osteomyelitis and bone tumors.
abstract: BACKGROUND
  Hematogenous osteomyelitis is often difficult to distinguish from a bone tumor because clinical findings are noncontributory and radiological features can mimic a bone tumor. Recently, the penumbra sign, a higher signal intensity feature of the thin layer of granulation tissue which lines the abscess cavity on T1-weighted magnetic resonance (MR) images, has been reported to be helpful for discriminating subacute osteomyelitis.
  
  
  OBJECTIVE
  To determine helpful findings for distinguishing osteomyelitis from bone tumors.
  
  
  METHODS
  The laboratory and imaging findings of a consecutive series of 244 patients referred to our institution with a suspected bone tumor were reviewed. There were 15 cases of osteomyelitis, 160 bone tumors, and 69 tumor-like lesions.
  
  
  RESULTS
  In osteomyelitis, the C-reactive protein (CRP) level increased in nine patients and the penumbra sign was seen in 11 patients. In bone tumors and tumor-like lesions, a high CRP level was observed in 21 patients and the penumbra sign was seen in two patients. The sensitivity of the penumbra sign for osteomyelitis was 73.3%, with a specificity of 99.1%.
  
  
  CONCLUSIONS
  The penumbra sign and a high CRP level support the diagnosis of osteomyelitis and may help to exclude the presence of a tumor.
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan. shimose@hiroshima-u.ac.jp
authors.forename: S
authors.initials: S
authors.lastname: Shimose
authors.forename: T
authors.initials: T
authors.lastname: Sugita
authors.forename: T
authors.initials: T
authors.lastname: Kubo
authors.forename: T
authors.initials: T
authors.lastname: Matsuo
authors.forename: H
authors.initials: H
authors.lastname: Nobuto
authors.forename: M
authors.initials: M
authors.lastname: Ochi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001859:Bone Neoplasms / Q000097:blood / Q000175:diagnosis*; D002097:C-Reactive Protein / Q000032:analysis; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000473:pathology; D006801:Humans; D006811:Humerus / Q000000981:diagnostic imaging / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D010019:Osteomyelitis / Q000097:blood / Q000175:diagnosis*; D011859:Radiography; D011884:Radius / Q000000981:diagnostic imaging / Q000473:pathology; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013977:Tibia / Q000000981:diagnostic imaging / Q000473:pathology
chemical_list: D002097:C-Reactive Protein