title: Tumors masked as frozen shoulders: a retrospective analysis.
abstract: BACKGROUND
  It was reported that some shoulder tumors were misdiagnosed with frozen shoulder syndrome. The purposes of this study were to elucidate the incidence of the initial misdiagnosis with frozen shoulder syndrome among the patients with malignant shoulder tumors, and to clarify whether such initial misdiagnosis affected the time to make a final correct diagnosis or not.
  
  
  METHODS
  Clinical records of 34 patients (age>40) with malignant shoulder tumors and those of 505 patients (age>40) with shoulder pain and stiffness were reviewed in the author's institute. The duration of the prediagnostic period was compared between the patients with and without an initial misdiagnosis as frozen shoulder syndrome.
  
  
  RESULTS
  Among 34 tumor patients, 9 (26%) had been initially misdiagnosed with frozen shoulder syndrome. Two patients actually manifested shoulder pain and stiffness, although they did not have a record of misdiagnosis. Among 505 patients with shoulder pain and stiffness, 4 (0.8%) were diagnosed later as having malignant tumors. One of these 4 patients had been initially misdiagnosed with frozen shoulder syndrome. Consequently, 15 malignant tumors (10 bone tumors and 5 soft tissue sarcomas) were identified. Seven of them were intraosseous humeral tumors and 4 were localized in the scapular region, where patients themselves could not find them. In 10 patients, initial misdiagnosis as frozen shoulder syndrome did cause a significant delay to reach the correct diagnosis as malignant tumors (P=.035).
  
  
  CONCLUSIONS
  Physicians should carefully re-examine the frozen shoulder patients with repeated plain radiographs followed by further imaging studies, if the conservative therapy fails.
authors: Department of Orthopaedic Surgery, Tohoku University School of Medicine, Sendai, Japan. staka@mail.tains.tohoku.ac.jp
authors: Hirotaka
authors: H
authors: Sano
authors: Masahito
authors: M
authors: Hatori
authors: Mitsuyoshi
authors: M
authors: Mineta
authors: Masami
authors: M
authors: Hosaka
authors: Eiji
authors: E
authors: Itoi
mesh_terms: D000328:Adult; D000368:Aged; D001707:Biopsy, Needle; D001859:Bone Neoplasms / Q000175:diagnosis* / Q000473:pathology; D002062:Bursitis / Q000175:diagnosis* / Q000473:pathology; D015331:Cohort Studies; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011336:Probability; D012189:Retrospective Studies; D018570:Risk Assessment; D012785:Shoulder Joint / Q000473:pathology*; D020069:Shoulder Pain / Q000175:diagnosis / Q000209:etiology; D012983:Soft Tissue Neoplasms / Q000175:diagnosis* / Q000473:pathology; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed