title: Prevalence of cartilaginous tumours as an incidental finding on MRI of the knee.
abstract: OBJECTIVE
  The purpose was to determine prevalence of enchondromas and atypical cartilaginous tumour/chondrosarcoma grade 1 (ACT/CS1) of the knee on MRI in a large cohort study, namely the Netherlands Epidemiology of Obesity (NEO) study.
  
  
  METHODS
  Participants aged 45 to 65 years were prospectively included, oversampling overweight and obese persons. Within a subgroup of participants, MRI of the right knee was performed and screened for incidental cartilaginous tumours, as defined by their characteristic location and appearance.
  
  
  RESULTS
  Forty-nine cartilaginous tumours were observed in 44 out of 1285 participants (estimated population prevalence 2.8 %, 95 % CI 2.0-4.0 %). Mean largest tumour diameter was 12 mm (range 2-31 mm). Eight participants with a tumour larger than 20 mm or a tumour with aggressive features were referred to rule out low-grade chondrosarcoma. One was lost to follow-up, three had histologically proven ACT/CS1 and four had dynamic contrast MRI findings consistent with benign enchondroma.
  
  
  CONCLUSIONS
  Incidental cartilaginous tumours were relatively common on knee MRI and may be regarded as a normal concurrent finding. However, more tumours than expected were ACT/CS1. Because further examination was performed only when suspicion of chondrosarcoma was high, the actual prevalence might be even higher.
  
  
  CONCLUSIONS
  • Incidental cartilaginous tumours are relatively common on knee MRI. • Most incidental cartilaginous tumours are small and lack suspicious features. • Small cartilaginous tumours without suspicious findings may be a normal concurrent finding. • Large tumours and/or those with suspicious findings should be further investigated. • Atypical cartilaginous tumour/chondrosarcoma grade 1 was found more often than expected.
authors.affiliation: Department of Radiology, C2-S, Leiden University Medical Center, P.O. Box 9600, 2300 RC, Leiden, The Netherlands. w.stomp@lumc.nl.
authors.forename: Wouter
authors.initials: W
authors.lastname: Stomp
authors.affiliation: Department of Radiology, C2-S, Leiden University Medical Center, P.O. Box 9600, 2300 RC, Leiden, The Netherlands.
authors.forename: Monique
authors.initials: M
authors.lastname: Reijnierse
authors.affiliation: Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands.|Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Margreet
authors.initials: M
authors.lastname: Kloppenburg
authors.affiliation: Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Renée
authors.initials: R
authors.lastname: de Mutsert
authors.affiliation: Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Judith V M G
authors.initials: JV
authors.lastname: Bovée
authors.affiliation: Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Martin
authors.initials: M
authors.lastname: den Heijer
authors.affiliation: Department of Radiology, C2-S, Leiden University Medical Center, P.O. Box 9600, 2300 RC, Leiden, The Netherlands.
authors.forename: Johan L
authors.initials: JL
authors.lastname: Bloem
mesh_terms: D000368:Aged; D001859:Bone Neoplasms / Q000453:epidemiology* / Q000473:pathology; D002356:Cartilage / Q000473:pathology; D002812:Chondroma / Q000453:epidemiology* / Q000473:pathology; D002813:Chondrosarcoma / Q000453:epidemiology* / Q000473:pathology; D015331:Cohort Studies; D005260:Female; D006801:Humans; D033162:Incidental Findings; D007719:Knee Joint / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D015995:Prevalence; D011446:Prospective Studies
keywords: Chondroma; Chondrosarcoma; Incidental findings; Knee; Magnetic resonance imaging