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.
Swan neck deformity is a deformed position of the finger, in which the joint closest to the fingertip is permanently bent toward the palm while the nearest joint to the palm is bent away from it (DIP flexion with PIP hyperextension). It is commonly caused by injury, hypermobility or inflammatory conditions like rheumatoid arthritis or sometimes familial (congenital, like Ehlers–Danlos syndrome). Pathophysiology
Swan neck deformity has many of possible causes arising from the DIP, PIP, or even the MCP joints. In all cases, there is a stretching of the volar plate at the PIP joint to allow hyperextension, plus some damage to the attachment of the extensor tendon to the base of the distal phalanx that produces a hyperflexed mallet finger. Duck bill deformity is a similar condition affecting the thumb (which cannot have true swan neck deformity because it does not have enough joints). Diagnosis
Diagnosis of swan neck deformity is mainly clinical. MRI of the hand may suggest volar plate attenuation of PIP and extensor tendon damage for DIP  Genetic screening tests such as for CMT disease may also be indicated. Treatment
Splinting for fingers. Passive stretching and clearing the deformity. References
External links
Swan neck deformity at Wheeless Textbook of Orthopedics, a technical review of the condition
Rheumatoid arthritis: Image showing deformities