This question has been asked in AIIMS May 2004 Paper. Although it is a simple question, this article covers a brief tutorial on the radiographic imaging of all bone tumours. ‘Sunray appearance” on x-rays is suggestive of : 1. a chondrosarcoma. 2. a metastatic tumor in the bone. 3. an osteogenic sarcoma. 4. an Ewing’s sarcoma. Plain radiography still has big role to play in arriving at accurate diagnosis in bone tumours, on the basis of five parameters. 1. The anatomical location of the lesion. The tumour can be grouped according to th anatomical location as follows: Diaphyseal : e.g. Ewing's Sarcoma Diaphysio Metaphyseal : e.g. Chondrosarcoma Metaphyseal : e.g. Osteosarcoma Metaphysio Epiphyseal : e.g. Giant Cell Tumour Aneury smal Bone Cyst. Epiphyseal : e.g. Chondroblastoma 2. The borders of the tuour. a. Well defined border, a narrow transitional area and a reactive sclerosis means a benign lesion. b. Poorly defined margins indicate a malignant lesion. 3. Bone destruction of a) geographic pattern (slow growth), b) moth eaten pattern (moderate prowth) or c) permeative pattern (rapid growth) 4. Matrix formation: New bone formation is another parameter to be observed and may vary from woolly masses to dense sclerosis. 5. Periosteal reaction is seen as non continuous and often laminated. e.g. Sunray appearance, Onion peel appearance. Computerised tomography is useful in the management in all stages, from initial diagnosis to final management and evaluation of dissemination. It denonstrate the extra osseous extension. It also help in early detection of pulmonary secondaries. Magnetic. Reasonance Imaging is a sensitive investigation to assess intramedullary and soft tissue extension of the tumour. Tc. 99 bone scan is essential for prebiopsy staging studies and also to determine dissemination. Angiogram is done before surgery for operation planning treatment and embolization. More recently. Digital subtraction Angiography (DSA) is being used. In this a real time image of the blood vessels alone is enhanced and the background details of bones and muscles are removed. This demonstrates the vascularity of the tumour.