title: An unusual knee mass in a soccer player.
abstract: BACKGROUND
  Non-traumatic knee joint effusion and fullness is a relatively common presenting complaint among athletes and non-athletes. Due to its broad differential diagnosis, a comprehensive evaluation beginning with history and physical examination are recommended. Imaging including plain radiography, magnetic resonance imaging (MRI), and in some cases ultrasound are preferred modalities. If inflammatory arthritis is suspected, joint aspiration and analysis may help diagnosis.
  
  
  METHODS
  A 37-year-old male soccer player presented with a complaint of left anterior knee pain and fullness for a few months. Physical examination revealed a healthy appearing male with obvious fullness of his left suprapatellar pouch and posterolateral knee. Plain radiographs were unremarkable. MRI demonstrated an effusion infiltrated by multiple, low intensity projections from a fatty mass in the suprapatellar pouch consistent with lipoma arborescens.
  
  
  CONCLUSIONS
  Lipoma arborescens is a rare synovial disorder characterized by replacement of subsynovial tissue with mature fat cells, most commonly in the knee joint. MRI is the best diagnostic modality to evaluate and confirm the diagnosis as well as rule out other pathologies. More recent single case-reports and clinical series endorse arthroscopic synovectomy as the treatment of choice.
authors.affiliation: Department of Family Medicine, School of Medicine, University of Colorado, Aurora, USA.
authors.forename: Morteza
authors.initials: M
authors.lastname: Khodaee
authors.affiliation: Department of Family Medicine, School of Medicine, University of Colorado, Aurora, USA.
authors.forename: David
authors.initials: D
authors.lastname: Roy
authors.affiliation: Department of Family Medicine, School of Medicine, University of Colorado, Aurora, USA.
authors.forename: Karin
authors.initials: K
authors.lastname: VanBaak
authors.affiliation: Department of Orthopedic Surgery, School of Medicine, Metro Health System and Case Western Reserve University, Cleveland, USA.
authors.forename: Blaine T
authors.initials: BT
authors.lastname: Bafus
keywords: Arthroscopy; Knee; Lipoma