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: Radiology
[{'content': "'Ely's cysts' are a feature of: \nSelect and explain. \nA. Osteoarthritis of TMJ, B. Chronic suppurative osteomyelitis, C. Fibrous dysplasia, D. Gorlin-Goltz syndrome", 'role': 'user'}, {'content': 'Answer: A \nExplanation: In severe degenerative joint disease (DJD), the glenoid fossa may appear grossly enlarged because of erosion of the posterior slope of the articular eminence. This erosion may allow the condylar\xa0 head\xa0 to\xa0 move\xa0 forward\xa0 and\xa0 superiorly\xa0 into\xa0 an\xa0 abnormal anterior\xa0 position\xa0 that\xa0 may\xa0 result\xa0 in\xa0 an\xa0 anterior\xa0 open\xa0 bite.\xa0 The condyle may also be markedly diminished in size and altered in shape\xa0 because\xa0 of\xa0 severe\xa0 erosions.\xa0 In\xa0 some\xa0 cases,\xa0 small,\xa0 round, radiolucent areas with irregular margins surrounded by a varying\xa0area of increased density are visible deep to the articulating surfaces. These lesions are called Ely cysts or subchondral bone cysts, but\xa0they\xa0are\xa0not\xa0true\xa0cysts;\xa0they\xa0are\xa0areas\xa0of\xa0degeneration\xa0that contain\xa0fibrous\xa0tissue, granulation tissue, and osteoid.\nOral radiology ; White and Pharaoh 7th edition page no: 509', 'role': 'assistant'}]