Aspirational biopsy of odontogenic keratocysts contains a greasy fluid which is pale in colour and contains keratotic squames. Protein content of cyst fluid below 4g% is diagnostic of odontogenic keratocysts. Smaller and unilocular lesions resembling other types of cysts may require a biopsy to confirm the diagnosis. On a CT scan, the radiodensity of a keratocystic odontogenic tumour is about 30 Hounsfield units, which is about the same as ameloblastomas. However, ameloblastomas show more bone expansion and seldom show high density areas.Radiographs of odontogenic keratocysts show well-defined radiolucent areas with rounded or scalloped margins which are well demarcated. These areas can be multilocular or unilocular. The growth pattern of the lesion is very characteristic from which a diagnosis can be made as there is growth and spread both forward and backward along the medullary cavity with little expansion. No resorption of teeth or inferior dental canal and minimal displacement of teeth is seen. Due to lack of expansion of the odontogenic keratocyst, the lesion can be very large when radiographically discovered. Differential diagnosis
Radiologically

Odontogenic myxoma
Ameloblastoma
Central giant-cell granuloma
Adenomatoid odontogenic tumor
Dentigerous cyst (follicular cyst)Histologically

Orthokeratocyst
Radicular cyst (particularly if the OKC is very inflamed)
Ameloblastoma

Histology
Odontogenic keratocysts have a diagnostic histological appearance. Under the microscope, OKCs vaguely resemble keratinized squamous epithelium; however, they lack rete ridges and often have an artifactual separation from their basement membrane.The fibrous wall of the cyst is usually thin and uninflamed.
The epithelial lining is thin with even thickness and parakeratinised with columnar cells in the basal layer which have focal reverse polarisation (nuclei are on the opposite pole of the cell). The basal cells are an indication of the odontogenic origin as they resemble pre-ameloblasts. The epithelium can separate from the wall, resulting in islands of epithelium. These can go on to form satellite or daughter cysts, leading to an overall multilocular cyst. Presence of daughter cysts is particularly seen in those with NBCCS. Inflamed cysts show hyperplastic epithelium which is no longer characteristic of OKCs and can have resemblance to radicular cysts instead. Due to areas of focal inflammation, a larger biopsy is required for correct diagnosis of odontogenic keratocysts. Treatment
As the condition is quite rare, opinions among experts about how to treat OKCs differ. A 2015 Cochrane review found that there is currently no high quality evidence to suggest the effectiveness of specific treatments for the treatment of odontogenic keratocysts. Treatment depends on extent of multilocularity and cyst. Small multilocular and unilocular cysts can be treated more conservatively through enucleation and curretage. Treatment options for KTOC may vary according to its size, extent, site, and adjacent structures. Treatment options:
Surgical enucleation: surgical removal of the entire epithelial lining of the cyst. Marsupialisation followed by enucleation: this method is carried out by surgeons for larger cysts. Curettage involving simple excision and scraping-out of cavity. Carnoys solution fixative (ethanol, chloroform and acetic acid) which is usually used in conjunction with excision and curretage.