Chondrosarcoma CT and MRI appearances
Sites:
The commonest sites are the pelvic bones,
the femur and humerus.
Other sites are the trunk,
the skull and facial bones.
Involvement of the hands and feet is rare.
Peculiar forms develop on laryngeal cartilage,
base of the skull,
or in soft tissue.
Chondrosarcomas may occur on pre-existing lesions.
Central chondrosarcoma predominates in long bones and peripheral tumours in the pelvis and vertebrae.
Central Chondrosarcoma
Plain films:
allow the depiction and location of the lesion,
identify its cartilagenous nature and its aggressiveness.
Medullary expansile osteolytic lesion of 1 to several cm in size With short transition zone with or without sclerotic margin
Well defined from host bone
Endosteal cortical thickening at a distance from the tumor due to invasion of Haversian system.
Central chondrosarcoma is the most frequent type of lesion.
The tumour begins in the metaphysis and extends to the diaphysis.
The lytic lesion usually appears well-defined,
associated with endosteal scalloping,
and cortical thinning or thickening.
High-grade tumours show irregular margins
Calcifications of the tumoral matrix may be punctate,
flocculent,
or have a ring-like pattern,
they can be small,
or disseminated,
dense or subtle.
Their absence is frequent in aggressive types
CT
has a diagnostic role as it shows the bony destruction,
the small calcifications,
and the intra and extra-osseous extent.
Geographic destruction
Chondroid matrix of Mineralization with rings and Arcs pattern in 70$
Non Mineralized portion is hypo dense to the muscle (high water content of hyaline cartilage)
Soft tissue extension
MRI
lobulated lesion with a low or intermediate signal on T1-weighted images and a high-signal intensity on T2 weighted images with foci of hypo intense matrix signal abnormalities due to mineralization/fibrous septae)
MRI allows for the precise staging of the medullary involvement and the soft-tissue mass
low-grade lesions show a lobulated pattern with enhanced septations after intravenous injection of contrast media.
High-grade tumours do not have septations and show a more diffuse,
heterogeneous enhancement
Main differential diagnosis is chondromas,
especially in the differentiation between a benign chondroma and a low-grade central chondrosarcoma following are mportant- Pain,
a proximal location or a location on the axial skeleton,
size being greater than 5 cm,
a lobulated aspect,
an ill-defined margin,
endosteal erosion and bone destruction with an extra-osseous component all suggest a malignant lesion
DDX: Benign enchondroma,
Osteo chondroma ,Osteo sarcoma,
MFH,Chordoma