Bizzare paraosteal osteochondromatous proliferation

  • Earlier called Turret exostosis
  • Affects proximal and middle phalanges of hand 
  • Metatarsals, long bones (femur and tibia) may be involved
  • 14-74 years of age
  • Painless mass
Imaging 
  • Well-defined lobulated mass
  • < 3 cm in size
  • Pedicle or sessile bony attachment
  • Underlying cortex intact
  • No true continuity of ossification
  • No mass or calcification in soft tissues
  • MR: low on T1, high on T2 and STIR. Integrity of underlying bone cortex strongly supports the diagnosis but is difficult to distinguish from paraosteal osteosarcoma