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': 'The radiolucency shown by the following radiograph is due to: \nSelect and explain. \nA. Nasopalatine cyst, B. Solitary bone cyst, C. Ameloblastoma, D. Nasolabial cyst', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Radiological signs\nThe nasopalatine cyst is located in the midline of the anterior palate and appears as a well-defined, round or ovoid radiolucency with a corticated margin (unless infected). The lesion may present rarely as a bi-lobular or heart-shaped radiolucency due to the simultaneous development of bilateral cysts. The presence of an intact lamina dura surrounding the maxillary central incisors is useful in distinguishing it from a radicular cyst, but as the lesion enlarges, lamina dura can be eroded. The distinction between a small cyst and a normal incisive foramen is usually made on size. The incisive foramen is typically about 6 mm in width but maybe as much as 10 mm anteroposteriorly. In addition, a normal incisive fossa is sharply delineated only at its lateral margin, whereas all margins of a nasopalatine cyst are well defined.\nKey Concept', 'role': 'assistant'}]