Keratocyst

What is Keratocyst?

A keratocyst is a rare benign lesion with an odontogenic origin that includes the mandible or maxilla supposedly arising from dental lamina. This type of cystic tumor proliferates and is one of the most aggressive odontogenic cysts amongst the oral cavity. It spreads in the adjacent bones and has high chances of re-growth. Keratocyst produces daughter cysts and outpouchings due to which it may re-occur.

Etiology 

Odontogenic keratocyst (OKCs) may develop due to:

  • Remnants of dental lamina (Seres rests)
  • Reduction of enamel epithelium of the dental follicle
  • Down growth or traumatic implantation of the basal cell layer of the epithelium surface
  • Genetic causes, especially PTCH gene aberration

Histology

  • Parakeratinized stratified squamous epithelium characterizes the odontogenic keratocyst
  • Cysts contain low protein level fluid
  • Absence of rete pegs in the epithelium
  • Parakeratinized stratified squamous epithelium has a thickness of 5-8 cell layers
  • Presence of Satellite cysts in the capsule
  • Basal cell layer of epithelium has a palisading arrangement of nuclei which looks like a ‘Tombstone’ or ‘Picket ‘

Radiology

It is visible as Lucent, solitary, corticated borders with the unilocular lesion. They usually expand in the maxillary sinus if present in the maxilla and grows in a length of the bone in anteroposterior dimension when present in the mandible. They sometimes result in the erosion of the root of the adjacent tooth.

Pathology

Origin of the odontogenic keratocyst is the epithelial cell rests which is present in the dental lamina and periodontal margin of the alveolus of the mandible.

Causes

The fundamental cause of keratocyst odontogenic tumor is the excision from the dental lamina. It mainly occurs from the dental lamina and the enclosed teeth.

Symptoms

Swelling and pain in severe conditions are the most common symptoms of keratocyst odontogenic tumor, but it can also be seen in dental X-Rays.

Diagnosis 

Cyst Contents (aspirate)

OKCs contain white, dirty, viscoid suspension of keratin which looks similar to pus but has a foul smell. The presence of keratin can be tested when:

  • Total protein lies below 4 g/100 ml
  • Electrophoresis contains low protein which is mostly albumin
  • Foul smell is examined for keratin cells

The keratocyst odontogenic tumor can be identified using:

  • Microscope
  • CT Scan

After diagnosis, doctors get a fair idea about the kind of cyst which may be:

  • Dentigerous cyst
  • Ameloblastoma
  • Calcifying odontogenic cyst (Gorlin cyst)

Treatment

The treatment depends somewhat upon how problematic the cyst is:

  • Local surgical excision
  • Curettage (cut and remove the cavity) & peripheral ostectomy
  • Enucleation& cryotherapy
  • Marsupialization, an open surgery with pouch creation within the mouth so that it is in contact with outside for a more extended period
  • Carnoy’s solution, used with excision

Odontogenic Keratocyst Recurrence

Recurrence of odontogenic keratocyst is very common because of the following reasons:

  • Supraepithelial split in the lining of the epithelial
  • Remnants of cell and daughter cysts
  • Basal layer budding
  • Cell proliferative activities in high level in the epithelial
  • Subepithelial split in the lining of epithelial
  • Surface layer being parakeratinized

References

  1. https://en.wikipedia.org/wiki/Keratocystic_odontogenic_tumour
  2. https://radiopaedia.org/articles/keratocystic-odontic-tumour
  3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3220151/
  4. https://radiopaedia.org/articles/keratocystic-odontic-tumour
  5. http://www.sciencedirect.com/sdfe/pdf/download/eid/1-s2.0-S0007117X72800271/first-page-pdf
  6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3783765/

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