Introduction
Odontogenic keratocysts (OKCs) account for 11.7% of all jaw cysts worldwide, making them the third most common type of cyst in the jaws after radicular and dentigerous cysts (1). OKCs are characterized by aggressive behavior and have a relatively high recurrence rate (2). Similar to other entities with an odontogenic origin, OKCs originate in tooth-bearing regions, and they occur twice as often in the mandible as in the maxilla (3). When OKCs originate in the mandible, the most common location is the posterior sextant, the angle or the ramus (4,5). Cases of OKCs often progress to the condyle because of their aggressive nature (6,7); however, to the best of our knowledge, only two reports of OKCs in the condyloid process that are not continuous with the surrounding areas have been reported (8,9). In both cases, OKCs occurred in the condylar head, which was resected. The present study reports on the case of an OKC that occurred discretely in the base of the condyle, which was treated successfully to preserve the condylar process.
Discussion
OKCs were initially described in 1876 and were named in 1956 by Phillipsen (12) to describe an odontogenic cyst lined with keratinized stratified squamous epithelium (13). In 1992, the term ‘odontogenic keratocyst’, which is synonymous with ‘primordial cyst’, was introduced by the World Health Organization (WHO) to denote benign cysts of odontogenic origin with a specific histological appearance. However, in 2005, this pathology was reclassified as a benign keratocystic odontogenic tumor (KCOT) in the third edition of the WHO classification of head and neck tumors because of the high risk of recurrence, aggressive clinical course, mutations in the protein patched homolog tumor suppressor gene, the occurrence of satellite cysts and the association with Gorlin-Goltz syndrome (14,15). However, due to insufficient evidence to categorize this pathology as a neoplastic lesion, in the fourth edition of the WHO classification of head and neck tumors, KCOT was moved back into the cyst category under the name OKC (16) and it is still categorized as a cyst in the current classification (fifth edition) (17).
The recurrence rate of OKC ranges between 7 and 28% (2). Since the 1980s, it has been suggested that to reduce the high recurrence rate of OKCs, surgery should include marginal resection, including a rim of uninvolved bone, which is similar to the treatment for unicystic ameloblastoma (18). Various suggestions have been made regarding surgical methods for OKCs. The main suggestions are as follows: Enucleation; enucleation plus adjunctive therapy, such as enucleation plus curettage, enucleation with Carnoy's solution, enucleation with cryotherapy and enucleation with peripheral ostectomy and Carnoy's solution; marsupialization; resection; or combinations of these techniques (2). Although the difference in recurrence rates due to the surgical method has been examined, several factors other than the surgical method contribute to the recurrence rate, such as multilocular cysts or unilocular cysts and perforated or nonperforated bony walls; therefore, there is no one-size-fits-all surgical procedure for OKC (2,19). There is another important consideration when choosing jawbone cyst surgery, which is the size of the cyst. Enucleation and primary closure are often selected. This technique is accepted for lesions <2 cm, in which angiogenic and osteogenic cells from the adjacent bone and periosteum can reach the remaining blood clot and could promote ossification (20). It was predicted that the OKC described in the present case report would create a cavity of >2 cm, including a reduction of the bone. Enucleation, followed by open packing, has been reported to be a less invasive method for the treatment of OKCs with a lower recurrence rate and this method was thus used in the present study (10,11). In the present case, after the packing became open, the tetracycline hydrochloride ointment gauze was replaced once a week and an impression was taken 1 month after the operation to create an obturator to prevent a dead space from collecting food or debris (21). As a result, a good healing course was observed without recurrence.
To the best of our knowledge, there have only been two reports of OKCs in the condyloid process that are not continuous with the surrounding areas (8,9). In both cases, OKCs occurred in the head of the condyle, which was resected. Although there is a difference between the condylar heads and the base of the condyle, the present case is the first in which the condylar process was successfully preserved. Although the details of the subsequent course were not described in the previous two cases, the excision of the articular process without reconstruction may result in malocclusion and facial deformity. In the present case, because the bone at the articular process was thinned, a hospitalization plan was made to avoid fractures. The patient received an oral liquid diet in the first 6 days after surgery, and during hospitalization, the patient was allowed only a minimum amount of mouth opening while eating or when brushing their teeth. In addition, from February to May 2021, an obturator was attached. A total of 20 months post-operation, the patient showed no signs of local recurrence.
In conclusion, this report presents a rare case of an OKC in the mandibular condyle base region of a 31-year-old man. Resection was performed under general anesthesia and the condylar process was successfully preserved. The patient has remained disease-free for 20 months post-operation.