title: Non-Radiographic Risk Factors Differentiating Atypical Lipomatous Tumors from Lipomas.
abstract: OBJECTIVE
  To determine non-radiographic risk factors differentiating atypical lipomatous tumors (ALTs) from lipomas.
  
  
  METHODS
  All patients with deep-seated lipomatous tumors of the extremities treated from January 2000 to October 2010 were retrospectively reviewed. Factors reviewed included age, gender, tumor location, size, histology, local recurrence, dedifferentiation, and metastasis. Multivariate logistic regression models were used to evaluate the effects of patient characteristics on ALT status.
  
  
  RESULTS
  Ninety-four lipomas and 46 ALTs were included. Patients with an ALT were older (median: 60.5 vs. 55 years). Lipomas were evenly distributed between upper (48.9%) and lower extremities (51.1%), whereas ALTs predominately involved the lower extremities (91.3%). Median ALT size (22 cm) was greater than lipomas (10 cm),p< 0.0001. One lipoma (1.04%) recurred at 77 months and five ALTs (10.9%) recurred at an average of 39 months (19-64 months). Two ALTs originally treated with wide resection recurred with a dedifferentiated component and were treated with wide re-excision and chemotherapy. No metastases or tumor-related deaths occurred in either group at the time of last follow-up. Patients older than 60 years, tumors greater than 10 cm, or thigh location, were more likely to be diagnosed with an ALT (p< 0.05).
  
  
  CONCLUSIONS
  Lipomatous tumors were more likely to be ALTs when the tumor was at least 10 cm in size, located in the thigh, or found in patients that were 60 years of age or older. These risk factors may be used to guide management and surveillance strategies, when lipomatous tumors do not display characteristic radiographic features.
authors.affiliation: Department of Orthopaedic Oncology, MD Anderson Cancer Center , Houston, TX , USA.
authors.forename: Justin E
authors.initials: JE
authors.lastname: Bird
authors.affiliation: Department of Orthopaedic Oncology, MD Anderson Cancer Center , Houston, TX , USA.
authors.forename: Lee Jae
authors.initials: LJ
authors.lastname: Morse
authors.affiliation: Department of Biostatistics, MD Anderson Cancer Center , Houston, TX , USA.
authors.forename: Lei
authors.initials: L
authors.lastname: Feng
authors.affiliation: Department of Pathology, MD Anderson Cancer Center , Houston, TX , USA.
authors.forename: Wei-Lien
authors.initials: WL
authors.lastname: Wang
authors.affiliation: Department of Orthopaedic Oncology, MD Anderson Cancer Center , Houston, TX , USA.
authors.forename: Patrick P
authors.initials: PP
authors.lastname: Lin
authors.affiliation: Department of Orthopaedic Oncology, MD Anderson Cancer Center , Houston, TX , USA.
authors.forename: Bryan S
authors.initials: BS
authors.lastname: Moon
authors.affiliation: Department of Pathology, MD Anderson Cancer Center, Houston, TX, USA; Sarcoma Research Center, Houston, TX, USA; MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Lazar
authors.affiliation: Department of Orthopaedic Oncology, MD Anderson Cancer Center , Houston, TX , USA.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Satcher
authors.affiliation: Department of Diagnostic Radiology, MD Anderson Cancer Center , Houston, TX , USA.
authors.forename: John E
authors.initials: JE
authors.lastname: Madewell
authors.affiliation: Department of Orthopaedic Oncology, MD Anderson Cancer Center, Houston, TX, USA; Sarcoma Research Center, Houston, TX, USA; MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: Valerae O
authors.initials: VO
authors.lastname: Lewis
keywords: atypical lipomatous tumor; lipoma; liposarcoma; well-differentiated liposarcoma