Nasolabial cyst occurs at-

Ans. is 'b' i.e., Union of nasal and maxillary process Nasolabial Cyst* Nasolabial cyst (also known as nasoalveolar cyst or Klestadt's cyst) is a rare non-odontogenic, soft-tissue, developmental cyst occurring inferior to the nasal alar region.* The cyst is derived from epithelial cells retained in the mesenchyme after fusion of the medial and lateral nasal processes and the maxillary prominence during fetal life or due to the persistence of epithelial remnants from the nasolacrimal duct extending between the lateral nasal process and the maxillary prominence.* Nasolabial cyst occur 3 times as commonly in women as men. Most patients present in the fourth decade of life.* The patient usually presents with a slowly enlarging asymptomatic swelling. Patients usually seek medical advice on secondary infection of the cyst or due to the resulting disfigurement.* On palpation, there is a non-tender, fluctuant, mobile swelling. The soft-tissue swelling may obliterate the nasolabial fold, elevate the ala or the floor of the nose (or both) and fill in the labial vestibule intraorally, with or without nasal obstruction.* The lesion may spontaneously rupture and drain orally, nasally or, occasionally via a cutaneous fistula.* Its treatment is surgical excision through sublabial incision. There is no tendency for recurrence if it was removed completely. Malignant transformation is rare.