软骨粘液纤维瘤的影像诊断

Chondromyxoid Fibroma,软骨粘液纤维瘤,Introduction,Chondromyxoid fibroma (CMF) is a rare, benign tumor of the bone CMF is most often found in the long tubular bones, especially the tibia and femur near the knee joint. CMF occurs predominantly in younger patients in the second or third decade of life.,The tumor arises from the cartilage-forming connective tissue of the marrow space. As its name implies, this benign cartilaginous neoplasm consists of chondroid, myxoid, and fibrous tissue in variable amounts, and microscopic evaluation of a wide area of the tumor may be necessary to identify all of the tissue subtypes.,Osteoclast-like giant cells may also be present, as may small cysts and hemorrhagic zones. Focal calcification is found microscopically in approximately one fourth of patients, although any gross evidence of calcification is rare.,Most CMFs (75%) occur in the bones of the lower extremity, particularly around the knee joint. CMF is localized to the femur and tibia in 50% of patients. The most common site is the proximal tibia, which accounts for approximately 30% of cases. The humerus, radius, and ulna also are affected.,In addition, the small bones of the foot are relatively common sites, and lesions of the hands, skull, spine, and pelvis have been reported.,Within the bone, the tumor typically originates in the metaphysis close to the physis. The tumor may extend into the epiphysis, the diaphysis, or both. Apophyses also may be affected (eg, the greater trochanter of the femur). In the long bones, the tumor is usually eccentric and ovoid in shape , with the long axis paralleling the length of the bone. In smaller bones, the tumor may occupy the entire volume of bone.,Preferred examination,Conventional radiography provides the most useful diagnostic information of any imaging modality; however, definitive diagnosis can only be made using analysis of biopsy specimens. Unless contraindicated, magnetic resonance imaging (MRI) is recommended over computed tomography (CT) scanning for delineation of tumor extent before surgery.,The tumor may extend into the diaphysis or, uncommonly, into the epiphysis. CMF may rarely be purely diaphyseal , but it is never solely epiphyseal. The tumor may replace the bulk of a smaller bone.,Limitations of techniques,Although findings on conv