- Discussion:
- locally painfull benign cartilaginous lesion of bone;
- it occurrs in adolescents;
- located in metaphyses of major long bones;
- this lesion most often presents as an active stage 2 lesion which is locally destructive & has a high recurrance rate (up to 25%);
- it does not undergo malignant transformation;
- Diagnostic Studies:
- radiographs reveal an eccentric radiolucent defect w/ no calcification;
- adjacent cortex may be expanded thinned or even absent;
- look for sclerotic and scalloped rim;
- typically located in the metaphyseal region of long bones, and in some cases it is possible for it to invade the epiphyseal plate;
- radiographic differential diagnosis:
- nonossifying fibroma and ABC;
- Histology:
- lobulated areas of spindle shaped cells and abundant myxoid or chondroid intercellular material;
- low magnification reveals lobulations;
- transition from hyaline cartilage to more cellular regions may be abrupt;
- shows immature myxoid cartilage w/ stellate shaped chondrocytes enmeshed in lightly staining myxomatous chondroid matrix;
- distributed throughout lesion are strands of benign fibrous tissue and small multinucleated giant cells;
- benign giant cells are usually seen between the lobules of tumor;
- pleomorphic cellular pattern is typical;
- diff dx:
- chondrosarcoma:
- in CMF pesence of large pleomorphic cells w/ hyperchromatic nuclei may result in false dx of chondrosarcoma;
- chondroblastoma:
- CMF may be indistinguishable from chondroblastoma, however, CMF is metaphyseal tumor whereas chondroblastoma is epiphyseal;
- Treatment:
- curettage is indicated for well encapsulated stage 2 lesions;
- stage 3 lesions, most often seen in the pelvis, require wide excision to prevent recurrance