Sunday, March 19, 2017

Chondroblastoma


General

  • Terminology: “giant cell variant” (1927) → epiphyseal chondromatous giant cell tumor → calcifying giant cell tumor → chondroblastoma
  • 1% to 2% of all primary bone tumors
  • 9% of all benign bone tumors
  • Mean age of 15-18 years
  • M >>F
  • Mean duration of symptoms 8.7 months
  • Trivia: Most common benign neoplasm of the patella

Imaging Features

  • Epiphysis/apophysis +/- metaphyseal/diaphyseal involvement
  • Metaphyseal/diaphyseal occurrence without epiphyseal/apophyseal involvement exceptionally rare
  • Proximal tibia >> proximal femur > distal femur > proximal humerus
  • Well-defined, sclerotic margins on radiographs
  • Can involve the cortex, resulting in expansion, thinning, or disruption.
  • Stippled matrix calcification seen in minority of cases
  • Periosteal reaction seen in majority of cases
  • Extensive peri-lesional edema on MRI is common
  • Homogeneously hypointense on T1
  • Variable on T2: can be diffusely hypointense, or have small cystic areas of increased T2 signal or fluid-fluid levels
  • Heterogeneous and moderate enhancement in solid portions. Less commonly, homogeneous and marked enhancement

Differential Diagnosis

Management/Prognosis

  • Curettage or resection
  • RFA (small lesions, small series, not common)
  • Local recurrence rate: 5.0% after curettage
  • Local recurrence rate: 0% after resection
  • Recurrence most frequent in the proximal humerus
  • Malignant transformation and benign pulmonary metastases extremely rare

References

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