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. Osteoclastoma, B. Osteochondroma, C. Ewing sarcoma, D. Lymphoma
A: Osteoclastoma
Answer: A: Osteoclastoma 
Explanation: Ans: a (Osteoclastoma) Ref: Maheswari, 3rd edSoap bubble appearance is seen in osteoclastomaClassical radiological featuresSoap bubble appearance- OsteoclastomaOnion peel appearance- Ewing sarcomaSunray appearance- OsteosarcomaCodman triangle- OsteosarcomaTrethowan signSlipped capital femoral epiphysisAneurysmal sign- TB spineLoss of horizontal striations and prominent vertical striations- Hemangioma vertebraChicken wire calcification- Chondrosarcoma