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
Polka dot appearance on CT scan is seen in which of the following? 
Select and explain. 
A. Ewing's sarcoma, B. Osteosarcoma, C. Vertebral hemangioma, D. Eosinophilic granuloma
C: Vertebral hemangioma
Answer: C: Vertebral hemangioma 
Explanation: 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