- See:
- Outside Links: Approaches To Differential Diagnosis In Musculoskeletal Imaging:
-
Soft Tissue Calcifications
-
Lucent Lesions of Bone
-
Sclerotic Lesions
- Discussion:
- note whether the bone formed in tumor is being produced by actual tumor cells or by normal osteoblasts reacting to tumor;
- while several benign tumors may form bone, only osteogenic sarcoma is a malignant bone forming tumor;
- host bone often responds to a tumor by combination of resorption and bone formation;
- reactive bone that forms the thin sclerotic border of slowly growing tumor may be mature lamellar bone;
- some tumors, such as typical
osteochondroma, are so characteristic that x-rays alone can establish the dx;
- in case of most bone tumors, and particularly those that destroy bone, dx cannot be established by roentgenographic means alone;
-
location of tumors:
- some tumors are found only in epiphysis, whereas others are most frequently seen in the metaphysis;
- smaller number are encountered in the diaphyseal region;
- some lesions occur most frequently before epiphyseal closure, whereas others are seen only after the epiphyses have closed;
-
ragiographic features:
- benign lesions are suggested if tumor is limited to the confines of bone, if it has well-demarcated
border surrounded by a thin rim of sclerotic bone, and if it has not broken through the cortex;
-
malignant lesions:
- are suggested if the boundaries of the tumor are ill-defined, if there are no sharp borders, if the lesion has a mottled
appearance, and if it has broken out of the confines of the bone and destroyed cortex, malignancy is to be suspected;
- malignant tumor cells that extend through the cortex may elevate periosteum and stimulate it to produce a small triangle
of reactive bone (Codman's triangle) where periosteum is lifted from the shaft;
- seen in
osteosarcoma and
Ewing's sarcoma but can also be found in
infections and hemorrhagic lesions;
- formation of new osseous tissue outside involved bone is suggestive of malignancy but can also be found in cases of infection
and in
myositis ossificans;
- small bony spicules radiating in a direction perpendicular to shaft, sunray effect, are frequently
found in osteogenic sarcoma but may be caused by other malignant, and even by some benign, processes;
- subperiosteal new bone formation, which has laminated or onionskin appearance, is seen in
Ewing's sarcoma, but it may
also be found in other conditions that elevate periosteum, such as
infection;
Magnetic resonance imaging in planning limb-salvage surgery for primary malignant tumors of bone.
