55-year-old male presented with chief complaints of swelling in the left leg for 4 months.

Plain radiograph of the left leg shows a large soft tissue mass in the region of the proximal femur with rings and arcs pattern of calcification and destrcution of the underlying bone.

Chondrosarcoma is a malignant tumor of chondrogenic origin that arises from chondroblasts and collagenoblasts. It is the third most common primary malignant bone tumor, following multiple myeloma and osteosarcoma and making up about 10% of all primary malignant bone tumors.

 Symptoms: Pain or swelling, or a combination of both.

Location: Most common sites are the pelvis and proximal femur (50%); other sites include proximal humerus (10%), ribs (15%), scapula (6%), distal femur and proximal tibia (7%), and craniofacial bones and sternum (5%).

 Large, radiolucent, round or oval lesion with poorly defined margins.

 Contours of the bone are enlarged or expanded. Metaphysis or diaphysis of long bones.

 Scalloping of the inner cortex (endosteum) is caused by the lobular out lines of the tumor.

 Cortex may be extensively eroded- indicates an advanced stage.

 Matrix of the lesion may have circular radiolucencies that represent large lobules of cartilage, imparting a bubbly appearance.

 Foci of irregularly scattered calcification in the tumor called as popcorn, fluffy, stippled, cotton wool, rings, and broken rings. 

 Soft tissue mass with heterogeneous contrast enhancement.

 T2 hyperintense signal in the non mineralized/calcified portions is highly suggestive of a chondroid matrix. Most demonstrate heterogeneous moderate to intense contrast enhancement.

1. Yochum T, Rowe L. Yochum and Rowe's essentials of skeletal radiology. Philadelphia, PA: Lippincott Williams & Wilkins; 2005.

2. Datir A. Chondrosarcoma .Radiology Reference Article. Radiopaedia.org Retrieved March 22, 2015. Available from: http://radiopaedia.org/articles/chondrosarcoma.

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55-year-old male with swelling in left leg for four months.

Image IQ: 55-year-old Male, Swelling in Leg