Thoracic Chondrosarcoma

thoracic chondrosarcoma

This 42-year old male presented with a large mass on left-side of the chest wall. The mass was noticed 5 years back and was growing particularly rapidly since last 1 year. Surprisingly, the only complaint was discomfort and interference during routine work.

Chondrosarcoma is the second most frequent primary malignant tumor of bone, representing approximately 25% of all primary osseous neoplasms. Chondrosarcomas are a group of tumors with highly diverse features and behavior patterns, ranging from slow-growing non-metastasizing lesions to highly aggressive metastasizing sarcomas. Chondrosarcoma is a
malignant tumor of cartilaginous origin, in which the tumor matrix formation is entirely chondroid in nature.

Chondrosarcomas are classified as central (originating within the intramedullary canal) or peripheral. Rarely, they may arise as juxtacortical lesions. Lesions are designated as primary when theyarise de novo or as secondary when they occur within a preexisting lesion such as an enchondroma or osteochondroma.

Axial lesions have a worse prognosis than those in the appendicular skeleton.

The age range is wide, but most cases occur in patients older than 40 years.

Secondary chondrosarcomas tend to occur in younger patients, namely, those aged 20-40 years. Chondrosarcoma is rare in children, but it tends to be aggressive.

Tumors are predominantly axial, and they most commonly involve the pelvic bones, femur, humerus, ribs, scapula, sternum, or spine. In tubular bones, the metaphysis is the most common site of origin. The proximal metaphysis is more frequently involved than the distal end of the bone.

Radiographs are essential for the initial diagnosis, and it is sometimes supplemented with CT, which is more sensitive for detecting matrix calcification and for confirming deep endosteal cortical scalloping in intramedullary tumors. MRI is the preferred modality for evaluating the extent of intramedullary tumors and demonstrating extraosseous extension. MRI is useful in evaluating the thickened cartilage cap in an osteochondroma that develops a secondary chondrosarcoma. MRI is less sensitive than CT in identifying small amounts of matrix calcification within a tumor. The presence of pain with any lesion (without a pathologic fracture in lesions of the hands and feet) is highly suggestive of malignancy. Other findings
suggestive of malignancy in a cartilaginous tumor include endosteal cortical scalloping of more than two thirds of the thickness of the cortex, ill-defined border and/or zone of transition, and a large soft tissue mass. Both benign and malignant cartilaginous tumors may show a central lucency. However, lucency of an area that previously showed matrix calcification is a highly suggestive feature. The size of the tumor is often poorly assessed on radiographs alone, and MRI is advised to demonstrate both the intramedullary and the soft tissue extent of the lesion. CT can be helpful in identifying matrix calcification in some lesions that appear entirely lucent on radiographs. In as many as 90% of cases, tumors appear as lucent areas containing chondroid matrix calcification. Endosteal scalloping and cortical destruction are frequently easier to appreciate on CT scans than on radiographs. CT can be used to guide percutaneous biopsy, and it is the modality of choice for investigating possible pulmonary metastatic disease. CT can often be used to successfully categorize the lesion as being of cartilaginous origin. Its medullary extent can be assessed more accurately with CT than with radiography. However, MRI is superior, and it is also the most useful modality for determining soft tissue extension.

References:
1. Resnik D, Kyriakos M, Greenaway GD: Tumors and tumor-like lesions of bone: imaging and pathology of specific lesions. In: Diagnosis of Bone and Joint Disorders. 4th ed. Philadelphia, Pa: WB Saunders Co; 2002: 3897-919.
2. Flemming DJ, Murphey MD: Enchondroma and chondrosarcoma. Semin Musculoskelet Radiol 2000; 4(1): 59-71

Credit: Dr Abhijit Datir