title: Differential diagnosis of primary benign and malignant retroperitoneal tumors.
abstract: BACKGROUND
  Clinical differential diagnosis between malignant and benign tumors is important in order to select a therapeutic strategy for a primary retroperitoneal tumor.
  
  
  METHODS
  The clinical findings and radiological features of 25 patients with primary retroperitoneal tumors were retrospectively evaluated to find those signs that might contribute to the preoperative distinction between benign and malignant tumors.
  
  
  RESULTS
  Of 25 primary retroperitoneal tumors, 15 were benign. This may reflect the increased number of incidentally found small benign tumors. There were significant associations between the presence of symptoms and malignancy (P < 0.05), between irregular margins on imaging and malignancy (P < 0.05) and between the absence of calcification and malignancy (P < 0.05). Malignant tumors were significantly larger than benign tumors (11.45 +/- 1.90 cm vs. 5.31 +/- 0.43 cm). A retroperitoneal tumor scoring system was developed to distinguish primary retroperitoneal benign tumors from their malignant counterparts based on the: 1) maximum diameter equal to or larger than 5.5 cm, 2) presence of symptoms, 3) absence of calcification, 4) presence of irregular margins, and 5) presence of cystic degeneration or necrosis. A significant correlation was found between the incidence of malignant tumors and the total retroperitoneal tumor score (P < 0.05).
  
  
  CONCLUSIONS
  This study suggests that the size of tumor, the presence of symptoms, irregular margins, and the absence of calcification may be valuable predictors of primary retroperitoneal malignant tumor.
authors.affiliation: Department of Urology, Keio University School of Medicine, Tokyo, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Nakashima
authors.forename: M
authors.initials: M
authors.lastname: Ueno
authors.forename: K
authors.initials: K
authors.lastname: Nakamura
authors.forename: M
authors.initials: M
authors.lastname: Tachibana
authors.forename: S
authors.initials: S
authors.lastname: Baba
authors.forename: N
authors.initials: N
authors.lastname: Deguchi
authors.forename: H
authors.initials: H
authors.lastname: Tazaki
authors.forename: M
authors.initials: M
authors.lastname: Murai
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003937:Diagnosis, Differential; D005260:Female; D005729:Ganglioneuroma / Q000000981:diagnostic imaging / Q000473:pathology; D006393:Hemangiopericytoma / Q000000981:diagnostic imaging / Q000473:pathology; D006801:Humans; D008210:Lymphocele / Q000000981:diagnostic imaging / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009442:Neurilemmoma / Q000000981:diagnostic imaging / Q000473:pathology; D010235:Paraganglioma / Q000000981:diagnostic imaging / Q000473:pathology; D012186:Retroperitoneal Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology*; D012512:Sarcoma, Ewing / Q000000981:diagnostic imaging / Q000473:pathology; D013724:Teratoma / Q000000981:diagnostic imaging / Q000473:pathology; D014057:Tomography, X-Ray Computed