title: Pigmented villonodular synovitis of the ankle: radiologic characteristics.
abstract: BACKGROUND
  Pigmented villonodular synovitis (PVNS) of the ankle is a rare benign proliferative growth of the synovium. Studies of the radiologic characteristics of ankle PVNS are sparse.
  
  
  METHODS
  To characterize the radiologic features of ankle PVNS, five patients with histologically proven ankle PVNS were retrospectively studied. The features of their radiographs, computed tomographic scans, and magnetic resonance images were reviewed, with emphasis on the morphological features, extension, margin, bone involvement, signal intensity, and degree of magnetic resonance enhancement.
  
  
  RESULTS
  All five lesions were diffuse, affecting the ankle and distal tibiofibular joint; three lesions also involved the subtalar joint. Radiography demonstrated extrinsic bone erosions with marginal sclerosis of the involved joints in all of the patients, but computed tomography identified this much better than did radiography. Magnetic resonance imaging revealed multiple lobulated soft-tissue masses in all of the cases. These soft-tissue masses surrounded the flexor hallux longus tendon and were hypointense on T1-weighted images, with a heterogeneous signal in two cases and homogenous hypointensity in three cases on fat-suppressed T2-weighted images. In one patient who underwent gadolinium-enhanced imaging, the masses showed intense enhancement.
  
  
  CONCLUSIONS
  Magnetic resonance imaging is the best way to reveal ankle PVNS. Magnetic resonance imaging findings of predominant hypointensity on all pulse sequences and standard radiography findings of bone erosion with marginal sclerosis are characteristic.
authors.affiliation: Radiology Department, Affiliated Hospital of Medical College Qingdao University, Qingdao, Shandong, China.
authors.forename: Da-Peng
authors.initials: DP
authors.lastname: Hao
authors.forename: Jian-Zhong
authors.initials: JZ
authors.lastname: Zhang
authors.forename: Wen-Jian
authors.initials: WJ
authors.lastname: Xu
authors.forename: Zhen-Chang
authors.initials: ZC
authors.lastname: Wang
authors.forename: Xue-Na
authors.initials: XN
authors.lastname: Wang
mesh_terms: D000368:Aged; D000843:Ankle Joint / Q000473:pathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D012189:Retrospective Studies; D013586:Synovitis, Pigmented Villonodular / Q000473:pathology*; D014057:Tomography, X-Ray Computed