Odontogenic Keratocyst Pathology

Odontogenic Keratocyst Pathology

Question. Define and classify odontogenic cysts of the oral cavity. Write in detail the etiopathogenesis, clinical features, investigations, and treatment of odontogenic keratocyst (OKC).
Answer. Odontogenic cysts are defined as those which arise from the epithelium associated with the development of teeth.

Odontogenic Keratocyst (Keratocyst Odontogenic Tumor)

It was given the term keratocyst odontogenic tumor (KCOT) because of its aggressive clinical behaviour depicting increased mitotic rate.

Odontogenic keratocyst pathology

Odontogenic Cysts of Oral Cavity Etiopathogenesis

• Odontogenic cyst is derived from cell rests of dental lamina or its remnants.
• It is derived from extensions of basal cells from the overlying oral epithelium.

Odontogenic Keratocyst Pathology: Causes, Symptoms, and Diagnosis

Odontogenic Cysts of Oral Cavity  Clinical Features 

• It occurs between 2nd and 3rd decades of life.
• Its predilection is more in males as compared to females.
• Mandible is affected more commonly than maxilla.
• In the mandible the majority of cysts occur in ramus third molar area, followed by first and second molar area and then the anterior mandible.
• It is asymptomatic unless they become secondarily infected in which case patient complains of pain, soft tissue swelling and drainage.
• Occasionally, patient experience paresthesia of lower lip and teeth.
• There is often one tooth missing from the dental arch.
• Expansion and thinning of bone may result in pathological fracture.
• Maxillary odontogenic keratocyst tends to be secondarily infected with greater frequency than the mandibular ones, due to its vicinity to maxillary sinus.

Odontogenic Cysts of Oral Cavity  Investigations 

Fine Needle Aspiration Cytology (FNAC)

• Appearance: Keratocystic odontogenic tumor (KCOT) contain a very characteristic thick, creamy, dirty white, viscoid suspension of keratin which has an appearance of pus but it is odorless.
• Smear: Smear of the aspirate should be prepared and stained and is examined under microscope for keratin cells.
• Electrophoresis: Aspirate will reveal low-protein content and high albumin to globulin ratio.
• Total protein estimation: Estimation of total protein will be found to be below 4 g/100 mL, which differentiates the lesion from other cystic contents.
• Cholesterol crystals, keratin squames, hyaluronic acid, Rushton bodies and heparin as well as chondroitin sulphate are found in aspirate
• Immunofluorescence: It demonstrates an antigen in the cystic fluid which is not present in other cystic lesions, nor in plasma or saliva and is known as keratocyst antigen.

OKC dental cyst features

Odontogenic Cysts of Oral Cavity  Radiography cysts 

An orthopantomogram (OPG) of the patient should be taken, which reveal following findings, i.e.

• Odontogenic keratocyst is oval in shape and it extends to the body of mandible with mediolateral expansion.
• It is very small in size or it can exceed the diameter of 5 cm.
• Margins of the cyst are hyperostotic.
• Mostly odontogenic keratocyst is unilocular and have smooth borders while some of the cysts show irregular borders too.
• Radiolucency is seen in the cystic part which appears to be hazy, if keratin is present in the cavity.
• Radiolucency is surrounded by thin sclerotic rim.
• In some of the cases, perforation of lingual and buccal cortical plates is seen.
• Displacement of inferior alveolar canal is seen downwards.

Odontogenic Cysts of Oral Cavity  Biopsy cysts 

Biopsy should reveal following histological features for odontogenic keratocyst:

• A parakeratin surface which is usually corrugated rippled or wrinkled.
• Uniformity of thickness of epithelium and is generally between 6 and 10 cells in depth.
• Prominent palisaded, polarized basal cell layer often described as having a “picket fence” or “tomb-stone” appearance.
• Occasionally, orthokeratin is found but if present, parakeratin is evident.
• Connective tissue shows “Daughter cells” or “Satellite cysts”, which are responsible for recurrence of OKC..
• The luman of keratocyst may be filled with thin straw colored fluid or with thick creamy material.
• Sometimes a lumen contains a great deal of keratin while at other times, it has little cholesterol as well as hyaline bodies at the site of inflammation.

Pathology of Odontogenic Keratocyst: Histopathological Features

Dental lamina remnants and OKC

Odontogenic Cysts of Oral Cavity  Treatment cysts 

• Treatment for odontogenic keratocyst is surgical, i.e.
• Enucleation: In this removal of cyst is done along with removal of cystic wall.
• Peripheral osteotomy: This procedure is carried out for reducing the chances of recurrence.
• Chemical cauterization: This is carried out along with enucleation. In this case carnoy’s solution is injected which leads to easy removal of cyst.