title: Pathological fracture of the patella due to an atypical located aneurysmal bone cyst: verification by means of ultrasound-guided biopsy.
abstract: BACKGROUND
  We report on a rare case of an atypical located aneurysmal bone cyst (ABC) in the patella presenting with pathological fracture after trauma.
  
  
  METHODS
  Using all available diagnostic modalities and by means of ultrasound-guided core-needle biopsy an unclear and suspected pathological fractured cystic bone lesion in the patella of a young man could be further clarified.
  
  
  RESULTS
  The acquired images suggested the diagnosis of a pathological fractured aneurysmal bone cyst after mild trauma. However, due to the extraordinary location and clinical presentation the diagnosis was secured by means of ultrasound-guided biopsy through a small cortical gap.
  
  
  CONCLUSIONS
  As shown in this rare case of an atypical aneurysmal bone cyst of the patella, the quite seldom but sometimes possible ultrasound-guided biopsy of intraosseous lesions can help to achieve the diagnostic clarification and should also be taken into account as a non-standard procedure.
authors.affiliation: Medical University Innsbruck Department of Radiology, Anichstraße 35, Innsbruck, 6020, Austria.
authors.forename: Michaela
authors.initials: M
authors.lastname: Plaikner
authors.affiliation: Medical University Innsbruck Department of Radiology, Anichstraße 35, Innsbruck, 6020, Austria.
authors.forename: Hannes
authors.initials: H
authors.lastname: Gruber
authors.affiliation: Medical University Innsbruck Department of Radiology, Anichstraße 35, Innsbruck, 6020, Austria.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Henninger
authors.affiliation: Medical University Innsbruck Department of Radiology, Anichstraße 35, Innsbruck, 6020, Austria.
authors.forename: Leonhard
authors.initials: L
authors.lastname: Gruber
authors.affiliation: Medical University Innsbruck Department of Trauma Surgery, Anichstrasse 35, 6020, Innsbruck, Austria.
authors.forename: Juana
authors.initials: J
authors.lastname: Kosiol
authors.affiliation: Medical University Innsbruck Department of Radiology, Anichstraße 35, Innsbruck, 6020, Austria. alexander.loizides@i-med.ac.at.
authors.forename: Alexander
authors.initials: A
authors.lastname: Loizides
mesh_terms: D000058:Accidental Falls; D062005:Biopsy, Large-Core Needle; D017824:Bone Cysts, Aneurysmal / Q000150:complications / Q000175:diagnosis*; D005598:Fractures, Spontaneous / Q000175:diagnosis* / Q000209:etiology; D006801:Humans; D061705:Image-Guided Biopsy; D007718:Knee Injuries / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging; D008297:Male; D010329:Patella / Q000000981:diagnostic imaging / Q000473:pathology*; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: Aneurysmal bone cyst; Patella; Pathological fracture; Ultrasound; Ultrasound-guided biopsy