Primary Central Chondrosarcomas And Enchondroma Of Long Bone Diagnosis And Differentiai Diagnosis

ObjectiveDefine the imaging features of primary central chondrosarcomas and enchondroma of long bone, in order to improve of the level of diagnosis and differential diagnosis.MethodsA retrospective study was performed on the imaging features of total 65 patients, 36 patients have histological diagnosis of primary central chondrosarcomas and 29 patients have histological diagnosis of enchondroma. The patients with enchondroma were classified as group A. The patients with chondrosarcoma were classified as group B. The group B were divided into group B1 representing low grade and B2 represnting high grade chondrosarcoma. Sixty-three patients had X-ray examination,59 patients had CT examination with multi-planner reformation (MPR). Fifty-six patients had MR scan, of which 40 patients had introvenous enhancement. The imaging studies were assessed for the tumor location (metaphysis, epiphisis, and shaft), size, longitudinal and width ratio, calcification (morphology, calcification of maximum level accounted for proportion of the tumor area), signal characteristics and enhancement manifestations of soft tissue mass, bone changes (cortical destruction, thickening of the bone cortex, periosteal reaction, endosteal scallopping, soft tissue tumors outside the bone, adjacent soft tissue and bone marrow edema, residual yellow marrow or internal bleeding of the tumor. The imaging features of each group were analyzed by SPSS 20 for Windows software to observe the differences between the groups. Using the fourfold table method to calculate the sensitivity, specificity and accuracy of each sign alone and combined in the diagnosis of high-grade chondrosarcoma.ResultsBoth Group A and B were generally found at metaphysis and epiphysis, commonly occur in the femur and humerus. The difference of tumor size, calcification of maximum level accounted for proportion of the tumor area, thickening of the bone cortex, endosteal scallopping, cortical destruction, soft tissue tumors outside the bone, and adjacent soft tissue and bone marrow edema were statistically significant between A and B groups, but had no significant difference between B2 and B1 groups. The optimal critical value of tumor size in the differential diagnosis of chondrosarcomas and enchondroma was 5.95 cm, while the type Ⅰ calcification and type Ⅲ enhancement were mainly found in the B2 group. The difference of longitudinal and width ratio of a mass were of no statistically significant between A and B groups, nor between B2 and B1 groups. While the presence of periosteal reaction, morphology of calcification and resideual yellow marrow within the tumor were of great statistically significant between both A, B groups and B1, B2 groups. Combined with other image feature inclduing soft tissue mass out side of the bone with endosteal scallopping in group B2 will increases the specificity upto 75%. If combined with type 1 calcification area ratio will further increase the specificity to 80%. The specificity of the type 3 enhancement in the diagnosis B2 group tumor was 93%, further combined with other image features did not improve the specificity.Conclusions1. Cartilaginous tumors of the long bones, if the maximum tumor diameter less than 6.0 cm with visible plaque like calcification, calcification greater than 2/3 of the total tumor size, without endosteal scallopping and/or thickening of the bone cortex, no significant periosteal reaction or soft tissue tumor outside the bone, MRI showed residual yellow marrow, with a circular arc-shaped enhancement, suggesting the diagnosis of enchondroma.2. If Maximum tumor diameter was greater than 6.0 cm, with punctate calcification, especially the ground glass like calcification, calcification is less than 2/3 of the total tumor size, the presence fo endosteal scallopping, cortical thickening, periosteal reaction and soft tissue tumor outside the bone, and with a nodular or mass-like enhancement, suggesting the diagnosis of chondrosarcoma. If calcification within the tumor area ratio is less than 1/3, without residual yellow marrow, accompanied with periosteal reaction or showing solid mass-like enhancement highly suggests a high-grade chondrosarcoma. Combined multiple imaging features can increase the specificity of the diagnosis.3. Calcification can be easily seen on CT, while MRI is better to show the tumor enhancement features, Bone destruction, residual yellow marrow wthin the tumor, bleeding, adjacent bone marrow, soft tissue edema and soft tissue tumors outside the bone. Combined MRI with CT scan will improve the diagnosis and differential diagnosis between benign and malignant chondroid tumor, provide more valuable information for patient’s management.