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': 'A 44 year old male presents to the OPD with a swelling on the palate. On intraoral examination, marked swelling is seen in the region of palatine papilla, situated mesial to the roots of 11 & 21. These teeth respond normally to vitality test. IOPA is given below. What is the most probable diagnosis? \nSelect and explain. \nA. Globulomaxillary cyst, B. Radicular cyst, C. Cyst of palatine papilla, D. Nasopalatine cyst', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Clinical feature\nThe age distribution is broad, with most cases being discovered in the fourth through sixth decades. The incidence is three times higher in males. Most of these cysts are asymptomatic or cause such minor symptoms that they are tolerated for long periods. The most frequent complaint\xa0 is a small, well-defined swelling just\xa0 posterior to the palatine papilla. This swelling usually is fluctuant\xa0 and\xa0 blue if the cyst is near\xa0 the surface. The deeper nasopalatine duct cyst is covered by normal-appearing\xa0 mucosa, unless it is ulcerated from masticatory trauma. If the cyst expands, it\xa0 may\xa0 penetrate\xa0 the\xa0 labial\xa0 plate\xa0 and\xa0 produce\xa0 a\xa0 swelling\xa0 below the maxillary labial frenum or to one side. The lesion also may bulge into the nasal cavity and distort the nasal septum. Pressure from\xa0 the\xa0 cyst\xa0 on\xa0 the\xa0 adjacent\xa0 nasopalatine\xa0 nerves\xa0 that\xa0 occupy the same canal may cause a burning sensation or numbness over.\nDifferential Diagnosis\nThe most common differential diagnosis is a large incisive foramen. A\xa0 foramen larger than 6 mm may simulate the appearance of a cyst. However, a clinical examination should reveal the expansion. A radicular cyst or granuloma associated with a central incisor is similar in appearance to an asymmetric nasopalatine cyst. The presence or\xa0 absence\xa0 of\xa0 the lamina dura and enlargement of the periodontal ligament space around the apex of the central incisor indicate an inflammatory lesion. A vitality test of the central incisor may be useful. characteristic of a cyst and other changes that occur with a space-occupying lesion, such as displacement of teeth.\nOral Radiology, Principles and Interpretation / Stuart C. White, Michael J. Pharoah - 7th ed pg-352', 'role': 'assistant'}]