title: Soft tissue sarcoma misdiagnosed as benign peripheral neurogenic tumor.
abstract: BACKGROUND
  Because of the distinctive clinical and MR findings associated with benign peripheral neurogenic tumors (BPNTs), they are commonly diagnosed without histological confirmation. As such, they are one of the most frequently misdiagnosed entities among the soft tissue sarcomas (STSs) that undergo initial unplanned excision. In this study, we investigate the characteristics of STSs misdiagnosed as BPNTs.
  
  
  METHODS
  We present a series of nine STS patients with an initial preoperative diagnosis of BPNT (BPNT-STS), and compare their clinical and MR findings to those of the 18 genuine BPNT patients, matched for site, depth, and size of tumors as well as related nerves.
  
  
  RESULTS
  Among the nine BPNT-STS cases, the most common histological diagnosis was synovial sarcoma (n = 4). Six patients (67 %) had deep-seated tumors; four patients (44 %) had tumors 5 cm or greater in size. BPNT-STS patients were more likely to experience pain (78 % vs. 22 %) and shorter symptom duration (9 vs. 55 months) compared to BPNT patients. A target sign on MR imaging was observed only in BPNT patients (0 % vs. 50 %), whereas peritumoral edema was found only in BPNT-STS patients (33 % vs. 0 %).
  
  
  CONCLUSIONS
  If a tumor suggestive of a BPNT is painful, with a relatively short symptom duration, and presents with peritumoral edema without a definite target sign on MR images, the possibility of an STS must be considered.
authors.affiliation: Department of Orthopaedic Surgery, Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul, 110-744, Korea.
authors.forename: Seungcheol
authors.initials: S
authors.lastname: Kang
authors.forename: Hye Jin
authors.initials: HJ
authors.lastname: Yoo
authors.forename: Han-Soo
authors.initials: HS
authors.lastname: Kim
authors.forename: Ilkyu
authors.initials: I
authors.lastname: Han
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002675:Child, Preschool; D003951:Diagnostic Errors; D005260:Female; D006258:Head and Neck Neoplasms / Q000175:diagnosis / Q000628:therapy; D006801:Humans; D035002:Lower Extremity; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009380:Neoplasms, Nerve Tissue / Q000175:diagnosis* / Q000628:therapy; D012189:Retrospective Studies; D012509:Sarcoma / Q000175:diagnosis* / Q000628:therapy; D012983:Soft Tissue Neoplasms / Q000175:diagnosis* / Q000628:therapy; D034941:Upper Extremity; D055815:Young Adult