title: Metachondromatosis: more than just multiple osteochondromas.
abstract: BACKGROUND
  Metachondromatosis is a rare genetic disease of osteochondroma and enchondroma formation, caused by loss of function of the PTPN11 gene. It is distinct from other similar conditions such as multiple osteochondromas and hereditary multiple exostoses by the distribution and orientation of lesions, and pattern of inheritance. Lesions typically occur in hands, feet, femora, tibiae and the pelvis. Lesions are typically reported to regress in adulthood.
  
  
  METHODS
  We reviewed the current literature on metachondromatosis, and present four new cases in a family with metachondromatosis.
  
  
  RESULTS
  Long-term follow up data reveal spontaneous regression of lesions by skeletal maturity. Complications may include nerve palsy due to the mass effect of lesions, avascular necrosis of the femoral head and angular deformity of long bones. Histopathological analysis has demonstrated that lesions in metachondromatosis are a mix of osteochondromas and enchondromas; however, one case of chondrosarcoma has been reported.
  
  
  CONCLUSIONS
  Lesions associated with metachondromatosis may cause a variety of complications due to mass effects; however, they are often asymptomatic, cause cosmetic concerns and, importantly, most regress spontaneously. Regular clinical review with selective imaging to monitor for such complications is appropriate, but uncomplicated lesions are unlikely to require surgical intervention.
authors.affiliation: Department of Orthopaedic Surgery, Women's and Children's Hospital, 72 King William Rd., North Adelaide, SA 5006 Australia.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Fisher
authors.affiliation: Department of Orthopaedic Surgery, Women's and Children's Hospital, 72 King William Rd., North Adelaide, SA 5006 Australia ; Centre for Orthopaedic and Trauma Research, University of Adelaide, Adelaide, Australia.
authors.forename: Nicole
authors.initials: N
authors.lastname: Williams
authors.affiliation: Department of Medical Imaging, Women's and Children's Hospital, Adelaide, Australia.
authors.forename: Lloyd
authors.initials: L
authors.lastname: Morris
authors.affiliation: Department of Orthopaedic Surgery, Women's and Children's Hospital, 72 King William Rd., North Adelaide, SA 5006 Australia ; Centre for Orthopaedic and Trauma Research, University of Adelaide, Adelaide, Australia.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Cundy
keywords: Case report; Enchondromatosis; Metachondromatosis; Osteochondroma; Review