Chondromyxoid Fibroma

- 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

Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Tuesday, July 3, 2012 9:44 am