This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Imaging of Musculoskeletal Tumors, Subject name: Radiology
[{'content': "Polka dot appearance on CT scan is seen in which of the following? \nSelect and explain. \nA. Ewing's sarcoma, B. Osteosarcoma, C. Vertebral hemangioma, D. Eosinophilic granuloma", 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. is \'c\' i.e., Vertebral hemangioma Characteristic radiological features of few bone tumorso Celery-stick appearanceEnchondromaso Coat-hanger appearanceOsteochondromao Codman tumor and chicken-wire calcificationChondroblastomao Double density sign on radionuclide scanOsteoid osteomao Nidus and sclerotic rimOstoid osteomao "Driven snow" appearancePindborg tumoro Fallen fragment/\'Hinged fragment signSimple (unicameral) bone cysto "Eggshell" covering of expansile cortex over surface of lesionABCo \' Soap bubble\' appearanceABCo Soap bubble appearance (& goes into comers)GCT (Osteoclastoma)o \'Floating tooth\' signEosinophilic granuloma, adamantinomao Onion skin (onion peel) appearanceEwing sarcomao Skip lesionsOsteosarcoma, Ewings sarcomao \'Sunrav/Sunburst\' appearanceOsteosarcomao String sign (to differentiate from myositis ossificans)Parosteal osteosarcomao Popcom/mottled calcificationChondrosarcomao Shepherd\'s crook deformityFibrous dysplasiao Codman\'s triangleOsteosarcoma, Ewing sarcomao Winking owl signMetastasis to pedicles of vertebrao Corduroy/accordian vertebra\'vertical striationsVertebra] hemangiomao Polka dot sign on CTVertebral hemangiomao Geographical skullEosinophilic granulomao Hole-within-a-hole lesionEosinophilic granuloma', 'role': 'assistant'}]