title: Imaging tumors of the patella.
abstract: BACKGROUND
  Patellar tumors are rare; only a few series have been described in the literature and radiographic diagnosis can be challenging. We reviewed all patellar tumors at one institution and reviewed the literature.
  
  
  METHODS
  In an evaluation of the database at one institution from 1916 to 2009, 23,000 bone tumors were found. Of these, 41 involved the patella. All had imaging studies and microscopic diagnostic confirmation. All medical records, imaging studies, and pathology were reviewed.
  
  
  RESULTS
  There were 15 females and 26 males, ranging from 8 to 68 years old (average 30). There were 30 benign tumors; eight giant cell tumors, eight chondroblastomas, seven osteoid osteomas, two aneurysmal bone cysts, two ganglions, one each of chondroma, exostosis, and hemangioma. There were 11 malignant tumors: five hemangioendotheliomas, three metastases, one lymphoma, one plasmacytoma, and one angiosarcoma.
  
  
  CONCLUSIONS
  Patellar tumors are rare and usually benign. As the patella is an apophysis, the most frequent lesions are giant cell tumor in the adult and chondroblastoma in children. Osteoid osteomas were frequent in our series and easily diagnosed. Metastases are the most frequent malignant diagnoses in the literature; in our series malignant vascular tumors were more common. These lesions are often easily analyzed on radiographs. CT and MR define better the cortex, soft tissue extension, and fluid levels. This study presents the imaging patterns of the more common patellar tumors in order to help the radiologist when confronted with a lesion in this location.
authors.affiliation: Department of Orthopaedic Oncology, Istituto Ortopedico Rizzoli, Bologna, Italy. Electronic address: roberto.casadei@ior.it.
authors.forename: R
authors.initials: R
authors.lastname: Casadei
authors.forename: J
authors.initials: J
authors.lastname: Kreshak
authors.forename: R
authors.initials: R
authors.lastname: Rinaldi
authors.forename: E
authors.initials: E
authors.lastname: Rimondi
authors.forename: G
authors.initials: G
authors.lastname: Bianchi
authors.forename: M
authors.initials: M
authors.lastname: Alberghini
authors.forename: P
authors.initials: P
authors.lastname: Ruggieri
authors.forename: D
authors.initials: D
authors.lastname: Vanel
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001175:Arthrography / Q000379:methods*; D001859:Bone Neoplasms / Q000175:diagnosis*; D002648:Child; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010329:Patella / Q000000981:diagnostic imaging* / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult