title: Dumbbell Scoring System: A New Method for the Differential Diagnosis of Malignant and Benign Spinal Dumbbell Tumors.
abstract: METHODS
  Retrospective diagnostic analysis.
  
  
  OBJECTIVE
  The aim of the study was to establish a new scoring system, the dumbbell scoring system (DSS), for preoperative evaluation of the malignant potential of spinal dumbbell tumors (SDTs).
  
  
  BACKGROUND
  Among SDTs, benign tumors such as schwannomas occur frequently, whereas malignant SDTs, including malignant peripheral nerve sheath tumors, are uncommon. No scoring system has been developed to preoperatively diagnose the malignant potential of SDTs.
  
  
  METHODS
  We retrospectively reviewed the records of 59 consecutive patients with SDTs. The following imaging features were recorded: tumor size, tumor shape, tumor boundary, pattern of enhancement of intratumoral lesions (homogeneous or heterogeneous), cyst formation in the tumors on magnetic resonance imaging, and enlargement of neural foramina and scalloping or osteolytic destruction of surrounding bones on computed tomography. The prevalence of characteristic imaging features in malignant and benign SDTs were evaluated, and appropriate cut-off points for the DSS score were obtained using receiver operating characteristics.
  
  
  RESULTS
  Twenty cases were confirmed to be malignant tumors. Pathological diagnoses of the malignant SDTs were as follows: 11 cases of malignant peripheral nerve sheath tumor; 3 cases of malignant lymphoma; and 1 case each of extraskeletal Ewing sarcoma, hemangiopericytoma, hemangioendothelioma, malignant myoepithelioma, neuroblastoma, and plasmacytoma. The DSS was based on four characteristic imaging features confirmed as significant predictors of malignant SDTs, namely, maximal diameter greater than 5 cm, irregularly lobulated tumor, tumor boundary indistinguishable from surrounding tissues, and osteolytic bone destruction. Malignant SDTs showed a higher DSS score (median 5.5 points) than did benign SDTs (median 0 point). The optimum cut-off value for the DSS score was 3 points, and the sensitivity and specificity for the diagnosis of malignant SDTs were 90% and 84.6%, respectively.
  
  
  CONCLUSIONS
  This scoring system may be helpful for preoperative decision making. If the DSS score is equal to or higher than 3, biopsies was recommended to confirm the histological diagnosis.
  
  
  METHODS
  4.
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Matsumoto
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Katsumi
authors.initials: K
authors.lastname: Harimaya
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Kawaguchi
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Mitsumasa
authors.initials: M
authors.lastname: Hayashida
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Okada
authors.affiliation: Department of Orthopaedic Surgery, Kyushu University Beppu Hospital, Beppu, Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Doi
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Yukihide
authors.initials: Y
authors.lastname: Iwamoto
mesh_terms: D000328:Adult; D003937:Diagnosis, Differential; D005260:Female; D006393:Hemangiopericytoma / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D006801:Humans; D008223:Lymphoma / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009442:Neurilemmoma / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013125:Spinal Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D014057:Tomography, X-Ray Computed / Q000379:methods