Mourshed showed that 33% of ameloblastomas arose from the epithelial lining of a dentigerous cyst. Although undeniably this can occur, the frequency of such neoplastic transformation is low. In addition, a squamous cell carcinoma may rarely arise in the lining of a dentigerous cyst. Transformation from normal epithelial cyst lining to SCC is due to chronic inflammation. It is likely that some intraosseous mucoepidermoid carcinomas develop from mucous cells in the lining of a dentigerous cyst. Malignancy in the cyst wall is usually unexpected at the time of presentation and the diagnosis is usually made following enucleation. Jagged or irregular margins with indentations and indistinct borders are considered to be suggestive of possible malignant change. Due to the potential for occurrence of an odontogenic keratocyst or the development of an ameloblastoma or, more rarely, mucoepidermoid carcinoma, all such lesions, when excised, should be submitted for histopathologic evaluation. Differential Diagnosis
The differential diagnoses of dentigerous cysts are as follows:

Radicular cystIt is an odontogenic cyst that is a sequela of periapical granuloma in a carious tooth. Odontogenic keratocyst(OKC)It is often multilocular and most commonly located in the body or the ramus of the mandible.Histologically, the epithelium is uniform in nature, usually four to eight cells in thickness. The basilar layer consists of a palisaded row of cuboidal to columnar cells that may demonstrate hyperchromatism. Characteristically, a corrugated or wavy layer of parakeratin is produced on the epithelial surface and desquamated keratin may be present in the cyst lumen.
Some dentigerous cysts may result in considerable displacement of the involved tooth. Infrequently, a third molar may be displaced to the lower border of the mandible or into the ascending ramus. On the other hand, maxillary anterior teeth may be displaced into the floor of the nasal cavity, while other maxillary teeth may be displaced through the maxillary sinus to the floor of the orbit. Furthermore, larger cysts can lead to resorption of adjacent unerupted teeth. Some dentigerous cysts may also grow to considerable size and produce bony expansion that is usually painless, unless secondarily infected. However, any particularly large dentigerous radiolucency should clinically be suspected of a more aggressive odontogenic lesion such as an odontogenic keratocyst or ameloblastoma. For this reason, biopsy is mandated for all significant pericoronal radiolucencies to confirm the diagnosis. The role of CT (computerized tomography) imaging in the evaluation of cystic lesions has been well-documented. CT imaging aids to rule out solid and fibro-osseous lesions, displays bony detail, and provides precise information about the size, origin, content, and relationships of the lesions.On CT imaging, a mandibular dentigerous cyst appears as a well-circumscribed unilocular area of osteolysis that incorporates the crown of a tooth. Displacement of adjacent teeth may be seen and they may be partly eroded. Dentigerous cysts in the maxilla often extend into the antrum, displacing and remodeling the bony sinus wall. Large cysts which may project into the nasal cavity or infratemporal fossa and may elevate the floor of the orbit can be noted on CT imaging.