Chondromyxoid Fibroma







  • Most cases of CMF occur in the metaphysis of tubular bones of the lower extremity.


  • Approximately one-third of the cases are diagnosed around the knee joint, especially the proximal tibial metaphysis which is the most common site of involvement and followed by the distal femoral metaphysis.


  • Rarely there are reports of cases that involve cortical bones.


  • Small bones of the feet are among the frequently involved site.


  • Upper extremity involvement is rare.


  • In the pelvis, the ilium is the most frequent site of involvement.


  • Other than that, there were reports to occur in the craniofacial bones, ribs, spine, clavicle, calcaneus, and sternum.



Clinical Symptoms and Signs






  • Clinically, patients present with pain that can persist for several months to several years or local swelling.


  • On very rare occasions, they suffer from rickets which is reported as an oncogenic osteomalacia.



Image Diagnosis



Radiographic Features






  • Mainly located in the metaphysis of long tubular bones and appears as a sharply circumscribed radiolucent lesion with an elongated shape of varying size of about 2–10 cm in largest diameter. Cortical expansion, exuberant endosteal sclerosis, and coarse trabeculation can be seen (Figs. 22.1 and 22.2).

    A312133_1_En_22_Fig1_HTML.jpg


    Fig. 22.1
    The radiograph of the distal femur shows an expansile osteolytic metaphyseal lytic lesion


    A312133_1_En_22_Fig2_HTML.jpg


    Fig. 22.2
    The radiograph shows a well-defined osteolytic bone lesion at the first metatarsal bone. The cortical margin is partially disrupted at the medial margin


  • Extensive periostitis and pathological fracture are rare, and calcification is infrequent.


  • The lesion is sharply defined and eccentrically located. Large lesions can be seen as hemispheric osseous defects with destruction of cortex.


  • Chondromyxoid fibroma arising in a flat bone may show irregular contours with osteolysis and bone expansion (Fig. 22.3).

    A312133_1_En_22_Fig3_HTML.jpg


    Fig. 22.3
    CT scan shows large irregular osteolytic and expansile lesion in a rib


CT Features






  • At CT, the extent of bone involvement can be better evaluated.


MRI Features






  • On MRI, chondromyxoid fibroma shows a multilobulated pattern, with low signal intensity on T1-weighted images and high signal intensity on T2-weighted images. With contrast injection, the central portion of the lesion may show no enhancement due to the myxoid component.


Image Differential Diagnosis



Chondrosarcoma






  • Chondrosarcoma may be mistaken for chondromyxoid fibroma and vice versa, especially if the lesion involves the pelvic bones. Chondrosarcoma usually has a more aggressive picture, is poorly circumscribed, and contains calcification.


Fibrous Dysplasia






  • FD shares, in numerous cases, the peripheral sclerosis seen in CMF, but the lesion is denser, with the so-called ground glass appearance in the center.


Pathology



Gross Features






  • Most often, CMF has been treated by curettage, so it is not usual to observe an intact gross specimen.


  • Curettage specimens are composed of a blue-gray or white tissue that rarely shows necrosis, cystic change, or liquefaction (Fig. 22.4).

    A312133_1_En_22_Fig4_HTML.jpg


    Fig. 22.4
    Gross features of chondromyxoid fibroma show yellow-white lobulated appearance


  • Typical hyaline cartilage is not present.


  • When the surrounding bone is available for evaluation, the tumor’s multilobulated appearance and sharp delineation from the bone can be appreciated (Fig. 22.5).

    A312133_1_En_22_Fig5_HTML.jpg


    Fig. 22.5
    Gross features of Fig. 22.3 show gray-white lobulated myxoid appearance (Courtesy by Soonchunhyang Hospital)


Histological Features






  • CMF has distinct microscopic features characterized by variably sized sharply demarcated lobules. These lobules vary in size, ranging from easily visible under low-power view to smaller ones (Fig. 22.6). The lobules tend to be hypocellular centrally with greater cellularity at the periphery (Fig. 22.7).

    A312133_1_En_22_Fig6_HTML.jpg


    Fig. 22.6
    Low power of chondromyxoid fibroma shows characteristic lobular configuration, relatively hypocellular and peripheral hypercellular areas


    A312133_1_En_22_Fig7_HTML.jpg


    Fig. 22.7
    At the periphery of the lobule, there are giant cells and mononuclear cells showing oval to spindle nuclei and pink cytoplasm


  • The lesional cells are spindled to stellate and are distributed in an abundant extracellular chondroid matrix (Fig. 22.8). Frequently, there is abundant pink cytoplasm, producing an epithelioid appearance (Fig. 22.9).

    A312133_1_En_22_Fig8_HTML.jpg


    Fig. 22.8
    In the lobule, elongated or stellate cells present in an abundant extracellular chondroid matrix


    A312133_1_En_22_Fig9_HTML.jpg


    Fig. 22.9
    At higher magnification, the central portion of tumor shows elongated to spindle, stellate cells admixed with myxoid stroma


  • The lobules are separated by fibrous bands (Fig. 22.10). The fibrous bands contain blood vessels and giant cells.

    A312133_1_En_22_Fig10_HTML.jpg


    Fig. 22.10
    The peripheral cells are more spindled to polyhedral shaped, simulating chondroblastoma, and appear to separate the lobules by fibrous bands


  • Approximately 50 % of CMF cases have scattered benign giant cells. Large bizarre hyperchromatic nuclei can be seen in 20–30 % of cases; however, they are usually focal and associated with large amounts of cytoplasm, sometimes with smudgy or degenerative features.


  • Mitoses are extremely rare in CMF, and atypical mitoses have not been noted.


  • Microscopic cystic or liquefactive change is uncommon and is usually focal, when present. Well-formed hyaline cartilage is present in less than 20 % of cases.


  • Calcification is present in about one third of cases, as either fine granules or denser and plaques (Fig. 22.11). Hemosiderin deposition is present at the lobular periphery associated with inflammatory cells and lymphocytes.
Jan 2, 2017 | Posted by in ORTHOPEDIC | Comments Off on Chondromyxoid Fibroma
Premium Wordpress Themes by UFO Themes