Epidemiological analysis of the clinicopathologic characteristics, treatment, and prognosis of 2648 jaw cysts in West China

To the Editor: The jaw cyst is one of the most common benign tumors in the oral and maxillofacial region.[1] To date, several studies have reported on jaw cysts in general populations from Italy, Brazil, Greece, and the United States in accordance with the 4th World Health Organization (WHO) classification of head and neck tumors.[2] However, there are no clinicopathological studies of odontogenic and non-odontogenic cysts in a large Chinese population in relation to the latest WHO classification. Furthermore, few epidemiological studies have analyzed treatment plans and the possible postoperative complications of jaw cysts. Consequently, this study aimed to perform a detailed and extended epidemiological analysis of jaw cysts in a large population in West China. We conducted a retrospective study of all histopathological confirmed jaw cysts that received surgical treatment from January 2015 to December 2020 at West China Hospital of Stomatology. This study was approved by the Institutional Review Board of West China Hospital of Stomatology, Sichuan University (No. WCHSIRB-D-2021-057) and followed the Declaration of Helsinki. The inclusion criteria were as follows: (1) Final pathological diagnosis of jaw cyst; (2) Received surgical treatment; (3) Complete records with no missing variables; and (4) Follow-up for at least 12 months. Follow-up consisted of oral examination and imaging data from plain radiography and/or cone beam computed tomography. Data were recorded from a review of medical charts and imaging data. The following information was collected and analyzed: Age, sex, anatomical location, clinical symptoms, radiological features, histopathological diagnosis, treatment modalities, and follow-up outcomes. Cysts were classified according to the 4th WHO classification[3] and previous literature[4] as follows: (1) Odontogenic cysts (radicular cyst [RC], dentigerous cyst [DC] and odontogenic keratocyst [OKC]); (2) Non-odontogenic cysts (nasopalatine duct cyst, median cyst, and nasolabial cyst); (3) Pseudocysts (simple bone cyst [SBC], static bone cyst, and aneurysmal bone cyst [ABC]). Jaw cysts can be categorized as either a single cystic lesion (only one compartment) or a multiple cystic lesion (multiple compartments). Concerning location, the site of onset was divided into the following nine regions: maxillary anterior (from canine to canine), maxillary premolars, maxillary molars, maxillary sinus, mandibular anterior (from canine to canine), mandibular premolars, mandibular molars, mandibular angle, and ramus. These cases were further divided into two age groups (≤16 years and >17 years) and then analyzed separately. Most jaw cysts were enucleated. In pediatric patients with DCs or large cysts, decompression was performed. Large jaw OKCs were treated with decompression combined with subsequent enucleation. Bone resection was performed for large multilocular cystic lesions with extensive erosion of the cortical bone or repeated recurrent cystic lesions. All statistical analysis was completed using IBM SPSS software (version 26.0; IBM, Armonk, NY, USA). All graph formations were performed using GraphPad Prism 6 (GraphPad Software, Inc., La Jolla, CA). The chi-squared test and Fisher’s exact test were used for continuous variables for comparison between groups with different surgical treatment procedures. A statistical difference between the groups was defined with a significance level of P <0.05. Throughout the 6 years, a total of 2307 patients were included in this study: 1383 males (59.95%) and 924 females (40.05%) with ages ranging from 0 to 89 years. Among these patients, 2107 patients (91.33%) had single jaw cysts, 200 patients (8.67%) had multiple (number of cysts >1) jaw cysts, and 25 patients had multiple types of jaw cysts. Among these cysts (N = 2648), 372 (14.05%) were diagnosed in patients aged 16 years and under, and 2276 (85.95%) were diagnosed in patients aged 17 years or older. Demographic and clinicopathological characteristics are presented in Table 1 and Supplementary Figure 1, https://links.lww.com/CM9/B930. Table 1 - Number of different types of jaw cysts in West China. Cyst Total ( N = 2332) Gender (male) Age (years, mean ± SD) Age group (years) 0–9 10–19 20–29 30–39 40–49 50–59 60–69 70–79 80–89 Radicular cyst 469 235 38.86 ± 15.87 6 46 100 92 101 72 39 12 1 Dentigerous cyst 469 316 33.83 ± 18.19 60 70 60 70 110 70 24 4 1 Odontogenic keratocyst 1272 770 38.52 ± 16.61 24 143 269 245 239 189 123 36 4 Nasopalatine duct cyst 64 50 37.34 ± 14.32 0 7 15 15 18 4 3 2 0 Median palatine cyst 4 3 24.60 ± 16.80 0 2 0 0 2 0 0 0 0 Simple bone cyst 47 21 24.89 ± 16.34 0 28 6 2 5 4 1 1 0 Static bone cyst 5 3 41.00 ± 15.31 0 1 0 0 3 1 0 0 0 Aneurysmal bone cyst 2 1 26.50 ± 17.68 0 1 0 1 0 0 0 0 0 * 25 patients had multiple types of jaw cysts, and thus the total cysts number is greater than that of the patients’ number. SD: Standard deviation. Supplementary Table 1, https://links.lww.com/CM9/B930 shows the distribution of odontogenic cysts (2523/2648, 95.28%), non-odontogenic cysts (69, 2.61%), and pseudocysts (56, 2.11%). The three most frequently diagnosed odontogenic cysts were OKCs (1506/2648, 56.87%), RCs (514/2648, 19.41%), and DCs (503/2648, 19.00%). Twenty-two cases represented OKC patients with nevoid basal cell carcinoma syndrome (NBCCS). The most frequent non-odontogenic cyst was the nasopalatine duct cyst, found in 2.42% of all cystic lesions. The site distribution of jaw cysts is shown in Supplementary Table 2, https://links.lww.com/CM9/B930. The mandible was more frequently involved than the maxilla with a ratio of 1.23:1.00. The mandibular molars and the anterior maxillary regions were the most commonly affected sites, with 35.95% (952/2648) and 31.08% (823/2648) of all cysts, respectively. Supplementary Tables 3 and 4, https://links.lww.com/CM9/B930 display the distribution of all jaw cysts in pediatric and adult populations, respectively. All the patients with jaw cysts had surgical treatment, including enucleation, decompression, resection, or a combination of these. Among the 2307 patients, 2167 patients (93.93%) had primary cystic lesions. One hundred forty patients (6.07%) received treatment in other hospitals, presenting at our department with recurrent cystic lesions, of which, 126 were OKCs, 12 were RCs, 1 was a nasopalatine duct cyst, and 1 was a DC. Among all 140 patients, 106 patients were treated with enucleation alone, 12 patients were treated with decompression, 4 patients were treated with decompression and second-stage enucleation, and 8 patients were treated with resection. In the recurrence analysis, we excluded 64 cases that received multiple surgical methods. Among the 2103 cases with primary cystic lesions, recurrence was observed in 32 cases (1.52%) after an observation period of 1.0–5.8 years (OKCs: n = 30, RCs: n = 2). Twenty-seven recurrences (1.43%) were found in 1893 patients treated with enucleation alone, two recurrences (1.36%) were observed in 147 patients treated with decompression alone, three recurrences (5.77%) were observed in 52 patients treated with decompression and second-stage enucleation, and no recurrence was found in 11 cases treated with resection. There was no statistically significant difference between the groups. In this study, we conducted the extended epidemiological analysis of jaw cysts in West China according to the 4th WHO classification of head and neck tumors. OKC (56.87%) was found to be the most common odontogenic cyst, followed by RC (19.41%). Many studies have reported that the RC is the most common odontogenic cyst based on populations from Iran, Italy, Brazil, and Canada.[1,5] One possible reason for this discrepancy is that our sample only included inpatients. Patients with smaller RCs can be treated as outpatients under local anesthesia. Another reason may be geographic differences, resulting in the higher incidence of OKCs in West China. The DC was found to be the third most frequent lesion, with a preference for the mandibular molar region, the anterior maxillary region, and the mandibular angle region. These localizations are consistent with previous studies. The mean age of onset of DCs was 33.83 years, with a frequency peak at 40 years old; This was higher than that reported in several studies. A possible reason for this difference is that DCs usually grow slowly and asymptomatically and are thus detected at a later age because of incidental radiographic findings. Non-odontogenic cysts represented 2.61% (69/2648) of all jaw cysts in our study. Some authors cited the nasopalatine cyst as the most frequently occurring non-odontogenic cyst,[6,7] corroborating the results of this study. We found 64 nasopalatine duct cysts, accounting for 2.42% (64/2648) of cases. Treatment of jaw cysts remains controversial. In our study, we compared the different surgical treatment procedures for treating jaw cysts in relation to the recurrence rate. Recurrence was found in 32 of 2103 cases (1.52%) of primary cystic lesions. There was no statistically significant difference between the groups treated by enucleation, decompression, decompression and second-stage enucleation, and resection. Therefore, cyst enucleation is recommended as the first choice of treatment for jaw cysts owing to its simplicity of surgery, minimal invasiveness, short treatment duration, and low impact on patients’ appearance and function. Bone resection was the treatment with the lowest recurrence rate. However, radical resection can cause facial deformity and poor oral function, and should be reserved for the treatment of large multilocular cystic lesions with extensive erosion of the cortical bone or repeated recurrent cystic lesions. In conclusion, our results showed that the OKC is the most frequent type of jaw cyst based on a large series sample in West China. Enucleation is recommended as the first choice for the treatment of jaw cysts. Acknowledgments The authors thank Xinnan Chang for the support of statistical analyses and Helen Jeays, BDSc AE, from Liwen Bianji (Edanz) (www.liwenbianji.cn), for editing the English text of a draft of this manuscript. Funding This study was supported by grants from the National Natural Science Foundation of China (No. 82100961) and the Applied and Basic Research Programs of the Sichuan Science and Technology Commission (No. 2020YJ0278). Conflicts of interest None.

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