ABSTRACT
Purpose To explore the clinical, imaging, pathologic features and diagnosis, treatment and prognosis of dedifferentiated chondrosarcoma (DDCS). Methods Forty cases of DDCS confirmed by pathologists were collected from Shanghai Jiaotong University Affiliated Sixth People's Hospital from January 2005 to August 2017, including clinical, imaging, pathologic and follow-up data. HE, immunohistochemistry and statistical methods were used with review of the related literature. Results There were 21 males and 19 females in 40 cases of DDCS, with an average age of 51 years. The tumors were located in hip, proximal femur, humerus, sternum, tibia, shoulder, finger, and thoracic cavity. The main clinical manifestations were local pain, swelling, limited mobility and so on. Typical radiographic manifestations are "bimorphic features", which showed two manifestations of dot or circular like calcification of chondrosarcoma, and invasive soft tissue masses. Histologically, clearly defined well-differentiated chondrosarcoma components juxtaposed highly malignant dedifferentiation components, which can display as follows: osteosarcoma, fibrosarcoma, malignant fibrous histiocytoma, and spindle cell sarcoma that could not be clearly classified. The dedifferentiated components might also be low-grade tumors such as giant cell tumor of bone or low grade osteosarcoma. The proportions of these two ingredients were uncertain. Preoperative biopsy was performed in 34 cases, of whom only 9 (26.5％) were correctly diagnosed as DDCS. The average survival time of patients with metastasis at first visit was significantly shorter than the patient without metastasis. Conclusion Diagnosis of DDCS should be combined with clinical features, imaging and histological morphology. As their histological morphology complex, and preoperative puncture biopsy limitations, its diagnosis is very difficult. Patients with metastases at the time of initial diagnosis have a worse prognosis.