Abstract
The keratocystic odontogenic tumour (KCOT) is one of the most aggressive odontogenic cysts and has a high recurrence rate. The treatment of these tumours is the subject of debate. A KCOT in the posterior maxilla with sinus involvement is rare. Few reports have been published in the literature. The purpose of this study was to evaluate the recurrence rate after surgical removal of maxillary KCOTs via a Le Fort I osteotomy. A search was performed to identify patients with a follow-up time of at least 5 years. Nine patients were included in the study. The following clinical variables were analyzed: age at surgery, sex, symptoms, site and size of the tumour, surgical approach, and recurrence rate. The surgical approaches were curettage ( n = 6) and enucleation ( n = 3). Recurrence was seen in three patients (33%); all had multilocular tumours. No recurrence was seen in patients with unilocular tumours. The Le Fort I osteotomy approach allows direct visualization and ensures wide excision, minimizing the risk of recurrence. In this series, cases with a multilocular KCOT showed a higher risk of recurrence due to the difficulty of removing the tumour in total. All recurrences took place within 2 years of the intervention; a 5-year follow-up is recommended.
The keratocystic odontogenic tumour (KCOT), previously known as odontogenic keratocyst (OKC), is a benign tumour originating from the dental lamina or its remnant, the basal cells of the oral epithelium, or cells of the dental follicle. This condition has been reported in both sexes, with an overall peak onset at around the second and third decades of life. Most previous studies have found a slight predominance in males. In the maxillofacial region, the site most affected is the posterior body of the mandible. The prevalence of KCOT in the maxillary sinus is still unknown.
The KCOT is characterized by aggressive growth and a high rate of recurrence. The recurrence rate varies between 0% and 60%, with an overall recurrence rate of 23–28% depending on the location of the tumour and the type of treatment. Most recurrences of KCOT have been observed within 5–7 years of the first treatment. However, KCOT may recur even 10 years after enucleation. The possible risk of recurrence therefore explains the need for long-term follow-up. The most common clinical manifestation is swelling or pain, or both. However, a variable proportion of cases (5.5–42.5%) have been diagnosed incidentally on routine radiographic examination.
Several imaging modalities have been used in patients with KCOT, including panoramic radiography, computed tomography (CT), cone beam computed tomography (CBCT), and magnetic resonance imaging (MRI). Radiographically, the tumours appear in a variety of shapes—often scalloped or multilobulated, with distinct margins. Thus, the condition has non-pathognomonic features. In 25–40% of cases, radiographic images reveal the involvement of an impacted tooth.
Several treatment strategies have been reported in the literature, including surgical management (enucleation, curettage, marsupialization, or resection) and adjuvant therapies such as Carnoy’s solution, electrocautery, or cryotherapy. The aggressive treatment of KCOT has been associated with a low recurrence rate, whereas more conservative methods tend to result in more recurrences. Resection with or without a continuity defect has a recurrence rate of 0%. However, on comparison with other less invasive procedures, this method has been criticized because of the benign nature of the disease.
Despite being benign in their biological behaviour, these tumours can become large (especially in the maxillary sinus) if they are not diagnosed in a timely manner and treated appropriately. Thus, a more extensive surgical approach is often used by surgeons to achieve acceptable radicality. The limited access to the tumours is considered to be one of the factors contributing to the high recurrence rate of KCOTs.
The Le Fort I osteotomy is one of the most commonly used surgical procedures for the correction of midface deformities; it offers a ‘panoramic’ view of the nasal cavity and maxillary sinus. In a study by Scolozzi et al., four patients with KCOTs in the maxillary sinus were treated through Le Fort I osteotomy and followed up for a period of 3–36 months. There were no signs of recurrence in these patients during the follow-up period. The use of other surgical approaches such as the Weber–Fergusson incision and Caldwell–Luc procedure has also been reported in the literature in case reports with a short follow-up period.
The purpose of this study was to describe the present authors’ experience of using the Le Fort I osteotomy for the removal of KCOTs extending into the maxillary sinus. The success rate and outcomes of the surgical technique were also assessed.
Materials and methods
Identification of the study population
A database search was done to find patients who had undergone Le Fort I osteotomy surgery and the surgical removal of cystic lesions over a 20-year period (1995–2015). The International Classification of Diseases, 10th revision (ICD-10) codes EEC.5 and EFA50 were used to identify subjects in the database. A review of the medical records was then performed to confirm the diagnosis. The inclusion criteria were (1) full documentation including surgical notes, (2) confirmed histopathological diagnosis, (3) a minimum follow-up period of 5 years, and (4) full radiographic documentation over the study period (CT or CBCT). Patients with tumours or bone metastatic tumours in the maxilla were excluded. Those with multiple cystic lesions associated with syndromes were also excluded.
All patients underwent biopsy preoperatively. Preoperative radiological examinations were performed by CT (seven cases) or CBCT (two cases). The presence of cystic lesions (size and shape) was evaluated by an experienced radiologist. The lesions were divided into two groups: unilocular (a single radiolucent cavity) and multilocular (bone wall dividing the lesion into two or more separate compartments).
Confounding factors and surgical techniques
Data on age at the time of surgery, sex, symptoms, site and size of the tumour, surgical approach, and recurrence were collected from the medical records.
The Le Fort I osteotomy performed on the study patients was that described by Obwegeser. A horizontal osteotomy was done with complete down-fracture through a circumvestibular incision. This was followed by full mobilization of the maxillary segment. Surgical removal of the tumours was performed either by enucleation or by curettage, as described by Gold et al.
The following definitions of enucleation and curettage apply to the patients included in this study. Enucleation is used when the lesion is separated from the surrounding bone via a connective tissue envelope. The lesion is easily excised in one piece. No bone is removed other than that required for surgical access. Curettage is reserved for lesions that adhere to the bone cavity without any encapsulating or circumscribing connective tissue envelope. After the lesion is removed, an inexact thickness of the surrounding bone may be removed with a burr, but bone continuity is preserved. Chemical or physical agents may also be used.
Statistical analysis
A descriptive statistical analysis was conducted and the results expressed as percentages or mean values. The hypothesis that patients who have undergone the surgical removal of a tumour within the sinus cavity via Le Fort I osteotomy will have a low recurrence rate was also tested.
Results
Demographic data and clinical manifestations
Fifteen patients were identified in the records. Six patients were excluded from the study because they were followed up for too short a time. Thus, data were collected for nine patients: four female and five male, with a mean age of 37 years (range 16–64 years). Four of the KCOTs were located in the right maxillary sinus and five were located in the left maxillary sinus. The most common symptoms were intraoral discharge ( n = 5) and pain ( n = 3) ( Table 1 ).
| Patient no. | Sex | Age (years) | Site | Size (mm) | Symptoms |
|---|---|---|---|---|---|
| 1 | M | 59 | Left sinus | 30 × 35 | Nasal discharge |
| 2 | M | 50 | Left sinus | 30 × 25 | Intraoral discharge |
| 3 | F | 64 | Left sinus | 30 × 17 | Nasal discharge |
| 4 | F | 20 | Right sinus | 20 × 29 | Pain, intraoral discharge |
| 5 | M | 23 | Right sinus | 20 × 27 | Pain, intraoral discharge |
| 6 | F | 16 | Left sinus | 30 × 35 | Intraoral discharge |
| 7 | M | 63 | Left sinus | 15 × 15 | Swelling, nasal discharge |
| 8 | M | 23 | Right sinus | 40 × 27 | Pain, intraoral discharge |
| 9 | F | 16 | Right sinus | 15 × 25 | Displacement of tooth (17) |
KCOT and treatment strategies
All patients underwent biopsy preoperatively. The preoperative histopathological diagnosis in these patients was consistent with the final histopathological diagnosis.
Of the nine patients included, three had undergone surgical treatment (Caldwell–Luc) of the KCOT before Le Fort I osteotomy surgery. One patient had a chronic oro-antral fistula due to removal of a maxillary third molar.
The most common type of treatment was curettage, which was used in six cases; enucleation was used in three cases. One of the patients had additional cryotherapy ( Table 2 ). None of the patients were treated with Carnoy’s solution.
| Patient no. | Previous treatment | Surgical approach | KCOT removed | Multilocular | Teeth removed | Follow-up period (years) | Imaging | Recurrence |
|---|---|---|---|---|---|---|---|---|
| 1 | Caldwell–Luc | Enucleation | In total | Yes | – | 16 | CT | Yes |
| 2 | Caldwell–Luc | Curettage | In pieces | Yes | 27 | 6 | CBCT | Yes |
| 3 | No | Curettage | In pieces | Yes | 26 | 8 | CT | Yes |
| 4 | No | Curettage | In total | No | 16, 17 | 7 | CBCT | No |
| 5 | Extraction of wisdom tooth | Curettage | In total | No | 17, 28 | 5 | CT | No |
| 6 | No | Enucleation | Easy | No | 28 | 8 | CT | No |
| 7 | No | Enucleation | In total | No | 18, 28 | 5 | CT | No |
| 8 | Caldwell–Luc | Curettage + cryotherapy | In total | No | 16 | 5 | CT | No |
| 9 | No | Curettage | In total | No | 18 | 5 | CT | No |
Follow-up and recurrence
During follow-up, the patients were assessed with either a CT scan ( n = 7) or CBCT ( n = 2), and the images were examined by an experienced radiologist ( Figs. 1 and 2 ).
Recurrence was seen in three patients ( Table 2 ). All three patients had had multilocular tumours in the left maxillary sinus. According to the surgical records from the first surgery, two of these patients had had tumours that adhered firmly to the surrounding bone and the tumours had been resected ‘in several pieces’. Two of the patients who presented with recurrence underwent a Le Fort I osteotomy to gain access to the lesions, and one underwent minor surgery under local anaesthetic. None of the patients had symptoms at the time of follow-up.
All three recurrences were seen on radiographs within 3 years of surgery ( Fig. 3 ). The mean time between the first surgery and the first signs of recurrence was 19 months (range 6–32 months). The mean time before a decision regarding second surgery was made was another 31 months (range 17–39 months). One of the patients had recurrence even after the second surgery. No further treatments were then performed because the patient had no symptoms and did not wish to undergo further surgery. The patient was followed clinically and radiologically.
