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From benign to controversial: Why do odontogenic keratocysts spark debate over classification?
Odontogenic keratocyst (OKC) is a rare and benign cyst that is locally aggressive. Most cases occur in the back of the jaw and are most common in the third decade of life. According to statistics, odontogenic keratocysts account for approximately 19% of all jaw cysts. Although it usually occurs in bony areas, it may affect soft tissue.
The reclassification of odontogenic keratocysts has caused considerable controversy in the dental cervical pathology community, with some pathologists still treating them as neoplasms consistent with the previous classification.
According to the classification of the World Health Organization (WHO) and the International Agency for Research on Cancer (IARC), odontogenic keratocysts were known as odontogenic keratocysts for many years and were reclassified as odontogenic keratocysts from 2005 to 2017. Keratocystic odontogenic tumor (KCOT). However, it was reverted to its previous name in 2017 because the new classification showed that UGAR was no longer considered a new organism and there was insufficient quality evidence to support this hypothesis, especially in terms of clonality.
Signs and symptoms
Odontogenic keratocysts can appear at any age but are more common in the third to sixth decade. The sex ratio is approximately 2:1. Most of the cysts are located in the lower jaw, and half occur at the angle of the jaw. Early stage odontogenic keratocysts usually do not show any symptoms, and clinical signs often include bony swelling or infection. However, because keratocysts grow due to epithelial proliferation rather than increased osmotic pressure, bone swelling is uncommon. When symptoms do occur, they often present as secondary symptoms of infection such as pain, swelling, and discharge.
Odontogenic keratocysts are usually discovered incidentally during imaging examinations. Single or multi-locular radioactive halos can be seen on imaging, which can be misdiagnosed as other types of cysts.
Cause
Odontogenic keratocysts originate from the odontogenic epithelium (dental lamina), which is the remaining fetal tooth body during tooth development. These cysts originate mainly from the remnants of Ceres.
Genetic factors
Nonsyndromic and syndromic odontogenic keratocysts are associated with mutations in the PTCH gene located on chromosome 9q, which is part of the Hedgehog signaling pathway. PTCH is a tumor suppressor gene, and the loss of its activity will cause the cell cycle to fail to function normally. Nearly one-third of odontogenic keratocysts display PTCH mutations, which result in high proliferative activity of the cyst epithelium, resulting in growth of the cyst wall and greater susceptibility to recurrence after resection.
Diagnosis
The diagnosis of odontogenic keratocyst usually relies on imaging examinations. However, a definitive diagnosis via biopsy is the final way to confirm the diagnosis. The keratocyst fluid removed by suction biopsy is light-colored, greasy, and contains keratinized flat cells. To confirm the diagnosis of small, unilocular tumors, a biopsy may be necessary.
On CT scans, the radiodensity of keratocysts is approximately 30 Hounsfield units, which is similar to odontoblastoma, but the latter tend to exhibit more pronounced bone expansion and less frequently show areas of high density. In imaging, odontogenic keratocysts can be seen as clear radiolucent areas with rounded or wavy edges, which can easily be misdiagnosed as other types of cysts and lack sensitivity.
Given the imaging characteristics of odontogenic keratocysts, careful diagnosis and follow-up examination are crucial.
Treatment and follow-up
Because this condition is relatively rare, experts differ on the treatment of odontogenic keratocysts. A 2015 Cochrane review showed that there is currently no high-quality evidence to support the effectiveness of specific treatments for odontogenic keratocysts. Treatment depends on the size and complexity of the cyst, with different surgical options such as surgical removal, cyst decompression, etc.
Follow-up should be performed regularly, with annual imaging studies, and long-term clinical follow-up is also very important, as relapses may occur many years after treatment.
The tumor nature of odontogenic keratocysts is still controversial. Some medical experts believe that due to its high recurrence rate, late detection and inactivation of tumor suppressor genes, it should be classified as a benign tumor. This point deserves further exploration: is an odontogenic keratocyst really a neoplasm?
