<prompt> X. Ray wrist showing soap bubble appearance in epiphyseal region. Diagnosis:Giant cell tumourOsteosarcomaOsteochondromaOsteoid osteoma  <response>: Ans. a Giant cell tumourRef: Maheshwari 5th ed. 1237; Orthopedic Pathology byVincent J Vigorita P 294 GCT is an epiphyseal tumor GCT usually involves subarticular region distal radius and distal femur, the proximal tibia being most common site. If there is a soap bubble appearance in diaphyseal region, it is adamantioma.Also Know Sun burst appearance: Osteosarcoma NiduSeed in cortex: Osteioid osteoma Onion skin appearance: Ewing s sarcoma Exostosis cartilage cap: Osteochondroma 