A 40-year-old patient, Ramu, has on X-ray an expansile solitary tumour in the centre of the femoral metaphysis with endosteal scalloping and presence of punctate calcification. The most likely diagnosis is

Ans-D Chondrosarcoma Chondrosarcoma - secondary changes in pre-existing cartilaginous lesion a. Common in forth and fifth decades. b. Patient may present as dull ache or a gradually enlarging lump, medullary lesion may presents as a pathological fracture c. Site - It may arise in any bone but is common in flat bones such as scapula, pelvis and ribs. X-ray - shows erosion of the cortex and bone destruction the tumor matrix may have mottled calcification typical of a cartilaginous tumor d. Primary chondrosarcoma: - shows a radiolucent area with central flecks of calcification, Rarely the tumour appears as a globular mass on the surface of the bones e. Secondary chondrosarcoma - shows bony exostosis, often surrounded by clouds of patchy calcification in the otherwise unseen lobulated cartilage cap, A tumour that is very large and calcification that is very fluffy and poor outlined are suspicious features.