Primary Bone Tumors

Bone TumorsBone tumors can be primary or secondary.Secondary (metastasis) tumors are the most common malignancy of bone.Primary bone tumors are divided into benign and malignant.Benign primary bone tumors are much more common than malignant primary bone tumors.

ImagingPrimary bone tumors, both benign and malignant often have specific radiographic appearances on plain film. MRI is used for local staging and to assess the position of the tumor in the medullary canal, degree of extracortical involvement, and proximity to surrounding structures.

Plain RadiographsAssess for:Precise locationUnderlying bony abnormalityWell-defined marginCortical expansion or destructionPeriosteal reactionSoft tissue mass

Benign LesionsRadiographic findings:

-Geographic pattern of bone destruction (well defined area of lysis) with a sclerotic rim.-Sclerotic rim (indicates that the bone has had time to react).-Solid periosteal reaction displaying focal cortical thickening.

Examples:

-Enchondroma-Aneurysmal bone cyst-Simple bone cyst-Nonossifying fibroma-Chondroblastoma

Malignant LesionsRadiographic findings:-Permeative pattern of bone destruction displays tiny radiolucencies between residual bone trabeculae (characteristic of rapidly growing, poorly defined lesions).-Poorly defined bone pattern-Periosteum shows separation from the cortex and formation of new bone. -codmans triangle-onion-skinningExamples:

-Osteogenic sarcoma-Ewings sarcoma-Chondrosarcoma

EnchondromaMetaphysis of tubular bones, ie small bones of the hands and feet.Lytic geographic lesion.Well-circumscribed oval lucencies. surrounded by a thin rim of radiodense bone.

Simple Bone CystProximal humerus and proximal femurcentral, well marginated & symmetricmetaphysis is not broader than with width of epiphyseal platethin rim of non-reactive bone borders the bone cyst

Nonossifying FibromaMetaphyseal or diaphyseal regions of distal femur or tibia.Eccentrically located, lobulated, surrounded by sclerotic margin.

Osteogenic SarcomaMetaphyseal region of distal femur and proximal tibia.Destroy surrounding cortices and produce soft tissue masses.Codmans triangle

Ewings SarcomaDiaphysis of femurDestructive, lytic lesion with permeative marginsOnion-skinning

ReferencesRobbins and Cotran. Pathologic Basis of Disease. 7th Edition.UMDNJ SOM Bone Tumor Pathology website.X-rays obtained on the web.

******Periosteum responds to traumatic stimuli or pressure from underlying growing tumor by depositing new bone. ******