This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bone Tumour, Subject name: Orthopaedics
Soap bubble appearance is seen in 
Select and explain. 
A. Giant cell tumour, B. Osteogenic sarcoma, C. Ewing's sarcoma, D. Osteoid osteoma
A: Giant cell tumour
Answer: A: Giant cell tumour 
Explanation: (Giant cell tumour) (181 -Apley's 8th)* Soap-bubble appearance due to ridging of the surrounding bone in Giant cell tumourX-Ray Appearance* Osteosarcoma - Sunray appearance**, Codman's triangle tumour new bone* Ewing's tumour - Onion - peel appearance*** Chondrosarcoma - Mottled calcification within the tumour* Simple Bone cyst - Well defined lobulated, radio lucent zone in the metaphysis or diaphysis of bone* Osteo chondroma - Large lesion shows "Cauliflower " appearance and degeneration and calcification in the centre of the cartilage cap