This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Unknown
[{'content': 'Comment on the X-ray \nSelect and explain. \nA. Acute osteomyelitis, B. Chronic osteomyelitis, C. Brodies abscess, D. Adamantinoma', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ref. Textbook of Orthopedics, Ebnezar. Page.527\n\xa0\nBrodie abscess\xa0is an intraosseous\xa0abscess\xa0related to a focus of subacute pyogenic\xa0osteomyelitis\n\nTypically these present in children with unfused epiphyseal plates, more frequently in boys.\xa0\n\n\nS. aureus\xa0(most common); cultures often negative\nThe “penumbra sign” on magnetic resonance (MR) imaging is useful for discriminating\xa0subacute osteomyelitis\xa0from other bone lesions.\nThe penumbra sign is a rim lining of an abscess cavity with higher signal intensity than that of the main abscess on T1-weighted images', 'role': 'assistant'}]