title: Differentiation of lipoma and atypical lipomatous tumor by a scoring system: implication of increased vascularity on pathogenesis of liposarcoma.
abstract: BACKGROUND
  Well-differentiated liposarcoma (WDL)/atypical lipomatous tumor (ALT) is considered a low-grade malignancy that rarely metastasizes but should be carefully followed because recurrence or dedifferentiation may occur. It is recognized that WDL and ALT are essentially synonymous, describing lesions that are identical both morphologically and karyotypically, and that site-specific variations in behavior relate only to surgical resectability. Preoperative differential diagnosis between lipoma and ALT has been well studied because their clinical and image characteristics are very similar. We evaluated the factors that may differentiate ALTs from lipomas, and validated a tentative scoring system for the diagnosis of the 2 tumor types.
  
  
  METHODS
  Forty-eight lipomas and 12 ALTs were included. The mean age, location and depth of the tumor as well as the compartment were not significantly different between the 2 groups. To evaluate the vascularity of the tumors, the average number of intratumoral vessels on pathological sections was calculated and compared between cases of lipoma and ALT.
  
  
  RESULTS
  The tumor size was significantly larger in ALT cases than in lipoma cases (P < 0.001). Magnetic resonance imaging (MRI) revealed septal structures in 91.6% of ALTs, whereas 20.8% of lipomas showed septa. Contrast enhancement in MRI was found significantly more often in ALTs (81.2%) than in lipomas (18.8%) (P < 0.001). We created a "ALT score" to discriminate between lipoma and ALT (0-6 points). ALT cases gave significantly higher point values (average 5.1 points) than lipoma cases (average 1.7 points) (P < 0.001). We found a significantly increased number of vessels in cases of ALT than in cases of lipoma (P = 0.001).
  
  
  CONCLUSIONS
  Our ALT score may help surgeons to differentiate a suspected ALT from a lipoma and could recommend a marginal resection in cases of suspected ALT. Increased intratumoral vascularity in ALT is reflected in the MRI findings and may play a key role in the acquisition of a malignant phenotype in adipocytic tumors.
authors: Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima-city, Kagoshima, 890-8520, Japan. naga@m2.kufm.kagoshima-u.ac.jp.
authors: Satoshi
authors: S
authors: Nagano
authors: Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima-city, Kagoshima, 890-8520, Japan. masahiro@m3.kufm.kagoshima-u.ac.jp.
authors: Masahiro
authors: M
authors: Yokouchi
authors: The Near-Future Locomotor Organ Medicine Creation Course (Kusunoki Kai), Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan. setoro@m2.kufm.kagoshima-u.ac.jp.
authors: Takao
authors: T
authors: Setoguchi
authors: Department of Medical Joint Materials, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan. ishidou@m2.kufm.kagoshima-u.ac.jp.
authors: Yasuhiro
authors: Y
authors: Ishidou
authors: Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima-city, Kagoshima, 890-8520, Japan. piro422@m2.kufm.kagoshima-u.ac.jp.
authors: Hiromi
authors: H
authors: Sasaki
authors: Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima-city, Kagoshima, 890-8520, Japan. mac1mickmick2@yahoo.co.jp.
authors: Hirofumi
authors: H
authors: Shimada
authors: Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima-city, Kagoshima, 890-8520, Japan. skomiya@m3.kufm.kagoshima-u.ac.jp.|The Near-Future Locomotor Organ Medicine Creation Course (Kusunoki Kai), Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan. skomiya@m3.kufm.kagoshima-u.ac.jp.
authors: Setsuro
authors: S
authors: Komiya
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D002454:Cell Differentiation; D003937:Diagnosis, Differential; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008067:Lipoma / Q000098:blood supply* / Q000145:classification / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009389:Neovascularization, Pathologic; D010641:Phenotype; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012189:Retrospective Studies; D047368:Tumor Burden