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?
Clinical feature
The 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  is a small, well-defined swelling just  posterior to the palatine papilla. This swelling usually is fluctuant  and  blue if the cyst is near  the surface. The deeper nasopalatine duct cyst is covered by normal-appearing  mucosa, unless it is ulcerated from masticatory trauma. If the cyst expands, it  may  penetrate  the  labial  plate  and  produce  a  swelling  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  the  cyst  on  the  adjacent  nasopalatine  nerves  that  occupy the same canal may cause a burning sensation or numbness over.
Differential Diagnosis
The most common differential diagnosis is a large incisive foramen. A  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  absence  of  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.
Oral Radiology, Principles and Interpretation / Stuart C. White, Michael J. Pharoah - 7th ed pg-352
Globulomaxillary cyst
Radicular cyst
Cyst of palatine papilla
Nasopalatine cyst