Management regulations for odontogenic keratocyst: a case report and review of the literature.

BACKGROUND: Reconstruction of the entire dentition with odontogenic keratocyst is a very challenging quandary. Most cases of odontogenic keratocyst are often reported to be benign, resulting in severe occlusal discrepancies with the maxillary and mandibular dentition. Dental radiographs occasionally reveal an uncommon, locally aggressive developing cyst termed as odontogenic keratocyst, which is typically located in the posterior jaw. When this cyst occurs in the anterior region, it is often misdiagnosed with other periapical lesions due to its lack of response to pulp vitality tests. CASE PRESENTATION: This clinical case scenario demarcates the endodontic management of a patient diagnosed with odontogenic keratocyst. A 37-year-old Indian male patient reported to the department with throbbing pain in the lower left posterior tooth requiring endodontic therapy. This patient also presented with odontogenic keratocyst in the anterior region of the jaw, for which he had undergone surgical rehabilitation. This case report highlights the clinical protocol for the endodontic therapy in patient diagnosed with ododntogenic keratocyst. Masticatory impairment was not visible after the follow-up period and the treatment outcome was successful. CONCLUSION: This case report details the presentation, characteristic radiographic findings, and endodontic management of a patient with an extremely rare condition of odontogenic keratocyst. The management involves multidisciplinary approach for the rehabilitation.

Recurrence of Glandular Odontogenic Cysts: A Systematic Review.

BACKGROUND: The glandular odontogenic cyst (GOC) is a benign developmental cyst of the jaws that is characterized by a high recurrence rate. METHODS: A systematic review is presented of reported cases, case series, and retrospective studies of recurrent cases of glandular odontogenic cysts, to determine the overall and detailed demographic features with documentation of the specific histologic features of the initial presentation of each cyst. Searches of detailed databases were carried out to identify articles published in the English language from 1988 to 2023. The variables were demographics, patient symptoms, cyst location, radiographic features, histopathological findings, type of treatment, and minimum eight months of follow-up. RESULTS: Eighteen cases were identified: with an equal gender presentation of 50% females and 50% males. The average age was 44.7. The mean size was 3.5 cm. The most common location was in the anterior mandible in 50% (n = 9) of cases, followed by the posterior mandible 27.8% (n = 5). Most patients were asymptomatic 55.6% (n = 10). The most common histologic features at first diagnosis were mucous cells in 88.9% (n = 16), variable thickness with 83.3% (n = 15), eosinophilic cuboidal cells 88.9% (n = 16), microcysts 83.3% (n = 15), and clear cells 77.8% (n = 14) cases. CONCLUSION: GOC has an aggressive behavior. Evidence was not conclusive to link any single or combination of histologic features to recurrence, and the strongest correlation for recurrence was the type of treatment. Since this is an uncommon cyst, more cases are needed. Follow-up should continue for at least five years, because recurrences were higher between years 3 and 5.

Glandular odontogenic cyst: Review of literature and report of two cases.

Glandular odontogenic cyst (GOC) is a rare developmental odontogenic cyst from the cell rests of Serres. GOC is locally aggressive with a tendency toward recurrence. The most common site of occurrence is the anterior mandible with an asymptomatic presentation. Radiographically, it presents as unilocular or multilocular radiolucency. It bears histopathological resemblance to low-grade mucoepidermoid carcinoma. We report two cases of GOC occurring in a 16-year-old and a 33-year-old male patient with a review of the clinical presentation, histopathological features, and diagnostic aspects of GOC reported so far in literature.

Assessment of MUC5AC and MUC2 Immunoexpression in Glandular Odontogenic Cysts, Dentigerous Cysts, and Mucoepidermoid Carcinomas.

Glandular odontogenic cysts (GOCs) and dentigerous cysts may show mucous metaplasia. Central mucoepidermoid carcinoma is very rare and mostly associated with dental cysts. It is hypothesized that odontogenic cysts showing mucus differentiation in their lining, have a propensity to transform into MEC. The present study is the first attempt to explore the relationship between odontogenic cysts [GOCs and dentigerous cysts with mucus metaplasia (DCMM)] and MEC by evaluating immunoexpression of MUC5AC and MUC2. Immunoexpression of MUC5AC and MUC2 was evaluated semiquantitatively in GOCs (20 cases), DCMMs (20 cases), and MECs (20 cases). The percentage of positive cells, intensity, and localization of immunoexpression were assessed for each marker in all cases. Of GOCs, DCMMs, and MECs cases, 85%, 70%, and 80%, respectively, were immunopositive for MUC5AC. Strong cytoplasmic immunoreactivity for MUC5AC was noted, particularly in mucous cells present diffusely within MECs. However, the immunoreactivity was limited to the epithelial lining of GOCs and DCMMs. Most of the MECs (60%) showed more than 25% positivity for MUC5AC, followed by GOCs, and the least in DMMCs. Mild cytoplasmic and nuclear positivity of MUC2 was noted only in epithelial lining cells of 70% GOCs and 45% DCMMs. Whereas, 55% of MECs displayed moderate to strong cytoplasmic and membranous immunopositivity for MUC2 exclusively within mucous cells. As MECs showed strong MUC5AC immunoreactivity in mucous cells, immunoexpression of MUC5AC in odontogenic cysts with mucus cells can possibly explain the pathogenesis of MEC from cysts. However, the variable expression of MUC2 did not give any strong evidence regarding its role as a marker.

In Silico Analysis of Genes Associated with the Pathogenesis of Odontogenic Keratocyst.

Odontogenic keratocyst (OK) is a benign intraosseous cystic lesion characterized by a parakeratinized stratified squamous epithelial lining with palisade basal cells. It represents 10-12% of odontogenic cysts. The changes in its classification as a tumor or cyst have increased interest in its pathogenesis. OBJECTIVE: Identify key genes in the pathogenesis of sporadic OK through in silico analysis. MATERIALS AND METHODS: The GSE38494 technical sheet on OK was analyzed using GEOR2. Their functional and canonical signaling pathways were enriched in the NIH-DAVID bioinformatic platform. The protein-protein interaction network was constructed by STRING and analyzed with Cytoscape-MCODE software v 3.8.2 (score > 4). Post-enrichment analysis was performed by Cytoscape-ClueGO. RESULTS: A total of 768 differentially expressed genes (DEG) with a fold change (FC) greater than 2 and 469 DEG with an FC less than 2 were identified. In the post-enrichment analysis of upregulated genes, significance was observed in criteria related to the organization of the extracellular matrix, collagen fibers, and endodermal differentiation, while the downregulated genes were related to defensive response mechanisms against viruses and interferon-gamma activation. CONCLUSIONS: Our in silico analysis showed a significant relationship with mechanisms of extracellular matrix organization, interferon-gamma activation, and response to viral infections, which must be validated through molecular assays.

Discovery of metabolite biomarkers for odontogenic keratocysts.

INTRODUCTION: Odontogenic keratocysts (OKCs) are locally aggressive and have a high rate of recurrence, but the pathogenesis of OKCs is not fully understood. We aimed to investigate the serum metabolomic profile of OKCs and discover potential biomarkers. METHODS: Metabolomic analysis was performed on 42 serum samples from 22 OKC patients and 20 healthy controls (HCs) using gas chromatography‒mass spectrometry to identify dysregulated metabolites in the OKC samples. LASSO regression and receiver operating characteristic (ROC) curve analyses were used to select and validate metabolic biomarkers and develop diagnostic models. RESULTS: A total of 73 metabolites were identified in the serum samples, and 24 metabolites were dysregulated in the OKC samples, of which 4 were upregulated. Finally, a diagnostic panel of 10 metabolites was constructed that accurately diagnosed OKCs (sensitivity of 100%, specificity of 100%, area under the curve of 1.00). CONCLUSION: This study is the first to investigate the metabolic characteristics and potential metabolic biomarkers in the serum of OKC patients using GC‒MS. Our study provides further evidence to explore the pathogenesis of OKC.

[Three-dimensional radiographic features of calcifying odontogenic cyst and calcifying epithelial odontogenic tumor].

OBJECTIVE: To analyze the three-dimensional radiographic characteristics of calcifying odontogenic cyst and calcifying epithelial odontogenic tumor using spiral computed tomography (CT) and cone-beam computed tomography (CBCT). METHODS: Clinical records, histopathological reports, and CBCT or non-enhanced spiral CT images of 19 consecutive patients with calcifying odontogenic cyst (COC) and 16 consecutive patients with calcifying epithelial odontogenic tumor (CEOT) were retrospectively acquired, and radiographic features, including location, size, expansion, internal structure and calcification, were analyzed. RESULTS: Among the 19 COC cases (12 males and 7 females, with an average age of 27 years), 89.5% (17/19) of the lesions originated from the anterior and premolar areas, 100.0% of them exhibited cortex expansion, and 78.9% had discontinued cortex. Among the 16 CEOT cases (3 males and 13 females, with an average age of 36 years), 81.3% (13/16) of the lesions were in the premolar and molar areas, 56.3% of them exhibited cortex expansion, and 96.8% had discontinued cortex. According to the distribution of internal calcifications, these lesions were divided into: Ⅰ (non-calcification type): absence of calcification; Ⅱ (eccentric marginal type): multiple calcifications scattered along one side of the lesion; Ⅲ (diffused type): numerous calcifications diffusely distributed into the lesion; Ⅳ (plaque type): with a ≥ 5 mm calcified patch; Ⅴ (peri-coronal type): multiple calcifications clustered around impacted teeth. Calcifications were present in 73.7% of COC lesions, including 9 type Ⅱ, 3 type Ⅲ and 2 type Ⅳ lesions, and 42.8% of CEOT lesions had calcification images, including 2 type Ⅲ and 5 type Ⅴ lesions. Six COC lesions had odontoma-like images. Moreover, 8 of 9 type Ⅰ CEOTs were histologically Langerhans cell-rich subtype, which had a smaller size (with an average mesiodistal diameter of 17.8 mm) and were not associated with impacted teeth. CONCLUSION: COC lesions tended to originate from the anterior part of the jaw and exhibit cortex expansion, and were sometimes associated with odontoma. CEOT commonly occurred in the posterior jaw and had discontinued cortex. Two lesions had significantly different calcification map. Over 70% of COC lesions had calcification images, which were mostly scattered along one side of the cysts, far from the impacted teeth. Approximately 60% of CEOT lesions exhibited smaller size and non-calcification, and the remaining CEOT cases often had calcification images clustered around the impacted teeth.

Long-term investigation of minimally invasive alcohol-based therapy as the treatment of odontogenic keratocyst:A retrospective cohort study.

The aim of this study was to evaluate the clinical efficacy of alcohol-based therapy for patients with large odontogenic keratocysts (OKCs). The study was implemented as a retrospective, single-center study. Patients treated with ethanol-based therapy for odontogenic keratocyst were retrospectively evaluated for baseline and postoperative data. The pre- and postoperative clinical situation and the extent of radiographic shrinkage were compared. The event is defined as the achievement of >50% reduction in cyst volume. The cyst reduction rate calculated on panoramic radiographs ranged from 7.4% to 99.9% (mean [standard deviation] 55.3% [27.9%]) and was statistically significant (P < 0.05). Specifically, it has been found that, radiographically, 47.6% of patients achieved >50% reduction in cyst volume within 12 months. The continuous cortical bone was rebuilt, and the cyst cavity was filled with regenerated trabecular bone. The 22 included patients presented with nonclinical problems, had no need for further intervention, and exhibited persistent impaction of the teeth. The results of this study demonstrated that ethanol-based therapy triggered marked radiographic reductions of large OKC, indicating that using this technique is efficient.

Digital pathology-based artificial intelligence models for differential diagnosis and prognosis of sporadic odontogenic keratocysts.

Odontogenic keratocyst (OKC) is a common jaw cyst with a high recurrence rate. OKC combined with basal cell carcinoma as well as skeletal and other developmental abnormalities is thought to be associated with Gorlin syndrome. Moreover, OKC needs to be differentiated from orthokeratinized odontogenic cyst and other jaw cysts. Because of the different prognosis, differential diagnosis of several cysts can contribute to clinical management. We collected 519 cases, comprising a total of 2 157 hematoxylin and eosin-stained images, to develop digital pathology-based artificial intelligence (AI) models for the diagnosis and prognosis of OKC. The Inception_v3 neural network was utilized to train and test models developed from patch-level images. Finally, whole slide image-level AI models were developed by integrating deep learning-generated pathology features with several machine learning algorithms. The AI models showed great performance in the diagnosis (AUC = 0.935, 95% CI: 0.898-0.973) and prognosis (AUC = 0.840, 95%CI: 0.751-0.930) of OKC. The advantages of multiple slides model for integrating of histopathological information are demonstrated through a comparison with the single slide model. Furthermore, the study investigates the correlation between AI features generated by deep learning and pathological findings, highlighting the interpretative potential of AI models in the pathology. Here, we have developed the robust diagnostic and prognostic models for OKC. The AI model that is based on digital pathology shows promise potential for applications in odontogenic diseases of the jaw.

Cysts and Benign Odontogenic Tumors of the Jaws.

This article addresses jaw lesions including cysts and benign odontogenic tumors in terms of their definition and clinical and imaging features and discusses pertinent differential diagnoses..

Immunohistochemical expression of SPARC in odontogenic keratocysts: a comparative study with other odontogenic cysts.

BACKGROUND: Secreted protein acidic and rich in cysteine (SPARC) has been shown to modulate aggressive behavior in several benign and malignant tumors. Little is known about SPARC expression in odontogenic keratocyst (OKC), an odontogenic cyst with an aggressive nature. To the best of our knowledge, only one study has been investigated the expression of this protein in OKCs. This study aimed to characterize SPARC expression in OKCs. Additionally, to determine whether SPARC is associated with aggressive behavior in OKCs, SPARC expression in OKCs was compared with radicular cysts (RCs), dentigerous cysts (DCs) and calcifying odontogenic cysts (COCs). These odontogenic cysts showed no or less aggressive behavior. METHODS: SPARC expression was evaluated in 38 OKCs, 39 RCs, 35 DCs and 14 COCs using immunohistochemistry. The percentages of positive cells and the intensities of immunostaining in the epithelial lining and the cystic wall were evaluated and scored. RESULTS: Generally, OKCs showed similar staining patterns to RCs, DCs and COCs. In the epithelial lining, SPARC was not detected, except for ghost cells in all COCs. In the cystic wall, the majority of positive cells were fibroblasts. Compared between 4 groups of odontogenic cysts, SPARC expression in OKCs was significantly higher than those of RCs (P < 0.001), DCs (P < 0.001) and COCs (P = 0.001). CONCLUSIONS: A significant increase of SPARC expression in OKCs compared with RCs, DCs and COCs suggests that SPARC may play a role in the aggressive behavior of OKCs.

Transformation of an odontogenic keratocyst into a solid variant of odontogenic keratocyst/keratoameloblastoma during long­term follow­up: A case report.

Keratoameloblastoma (KA) and solid variant of odontogenic keratocyst (SOKC) are rare odontogenic lesions, and their relationship and differences are unclear. The present study described a case that started as an odontogenic keratocyst (OKC) and transformed to SOKC/KA upon recurrence. Briefly, a 26­year­old man presented with swelling in the right cheek and was referred to the Department of Oral and Maxillofacial surgery, Hiroshima University Hospital (Hiroshima, Japan). At the initial visit, unicystic bone permeation was observed extending from the right canine to the molar, maxillary sinus and nasal cavity. After the biopsy, the patient underwent excisional surgery and was diagnosed with OKC. Thereafter, the lesion recurred six times over a period of 13 years and showed different histopathological features from those of the primary lesion, all consisting of numerous cysts with keratinization, which were diagnosed as SOKC/KA. The Ki­67 positivity rate was ~10%, which was higher than that of the primary lesion, but there was no atypia. Genetic analysis of the recurrent lesion revealed mutations in adenomatous polyposis coli and Kirsten rat sarcoma viral oncogene homolog. This case originated from OKC, and the morphological features of OKC and KA were mixed upon recurrence, supporting the commonality and association between the two. However, multiple mutations different from those of OKC and ameloblastoma were detected, suggesting an association of SOKC/KA with increased proliferative activity and a high recurrence rate.

The IL-1ß-p65 axis stimulates quiescent odontogenic epithelial cell rests via TGF-ß signalling to promote cell proliferation of the lining epithelia in radicular cysts: A laboratory investigation.

AIM: Cyst formation of the jaws is frequently accompanied by the proliferation of odontogenic epithelial cells located in the periodontal ligament (PDL), which consists of heterozygous cells and includes the most fibroblasts. The lining epithelium of radicular cyst, an odontogenic cyst of inflammatory origin, is derived from the proliferation of the remnants of the Hertwig epithelial root sheath (odontogenic epithelial cell rests of Malassez; ERMs) in the PDL. ERMs are maintained at a lower proliferative state under physiological conditions, but the regulatory mechanisms underlying the inflammation-dependent enhanced-proliferative capabilities of ERMs are not fully understood. The aim of this study was to evaluate the effects of cytokine pathway association between TGF-ß signalling and IL-1ß signalling on the regulation of odontogenic epithelial cell proliferation using radicular cyst pathological specimens and odontogenic epithelial cell lines. METHODOLOGY: Immunofluorescence analyses were performed to clarify the expression levels of Smad2/3 and Ki-67 in ERMs of 8-week-old mouse molar specimens. In radicular cyst (n = 52) and dentigerous cysts (n = 6) specimens from human patients, the expression of p65 (a main subunit of NF-κB), Smad2/3 and Ki-67 were investigated using immunohistochemical analyses. Odontogenic epithelial cells and PDL fibroblastic cells were co-cultured with or without an inhibitor or siRNAs. Odontogenic epithelial cells were cultured with or without TGF-ß1 and IL-1ß. The proliferative capabilities and Smad2 phosphorylation levels of odontogenic epithelial cells were examined. RESULTS: Immunohistochemically, Smad2/3-positivity was increased, and p65-positivity and Ki-67-positivity were decreased both in ERMs and in the epithelial cells in dentigerous cysts, a non-inflammatory developmental cyst. In contrast, p65-positive cells, along with the expression of Ki-67, were increased and Smad2/3-positive cells were decreased in the lining epithelia of radicular cysts. Co-culture experiments with odontogenic epithelial cells and PDL fibroblastic cells revealed that PDL cells-derived TGF-ß1/2 and their downstream signalling suppressed odontogenic epithelial cell proliferation. Moreover, TGF-ß1 stimulation induced Smad2 phosphorylation and suppressed odontogenic epithelial cell proliferation, while IL-1ß stimulation reversed these phenotypes through p65 transactivation. CONCLUSIONS: These results suggest that IL-1ß-p65 signalling promotes odontogenic epithelial cell proliferation through suppressing TGF-ß-Smad2 signalling, which would be involved in the pathogenesis of radicular cysts.

Dentigerous cysts suspected the other odontogenic lesions on panoramic radiography and CT.

Dentigerous cysts are known as the second most common type of cyst in the jaws. The cyst is one of the lesions occurred frequently in the posterior body of the mandible and is often related to the unerupted third molar and forms around the crown of the unerupted tooth attaching at the cementoenamel junction. Such characteristic appearances are the diagnostic points differentiating from ameloblastoma or odontogenic keratocyst. However, it would be hard for us to diagnose it as a dentigerous cyst if the lesion does not show its typical appearance. We experienced two cases of dentigerous cysts which did not form around the crown of the unerupted tooth on radiologically. Both cysts were relatively large and resorbed adjacent teeth roots. Therefore, an ameloblastoma or an odontogenic keratocyst was suspected rather than a dentigerous cyst as the imaging diagnosis. The biopsy revealed that the lesion was a "dentigerous cyst" in one of the cases and "developmental cyst with inflammation" in another case. After the excision, the histopathological diagnosis was a dentigerous cyst with inflammation in both cases. This report shows the two cases of dentigerous cysts focusing on panoramic radiography and CT images. Also, we discuss the differential diagnosis by reconsidering those diagnostic points.

Immunohistochemical Comparison of Ki-67 and MCM-3 in Odontogenic Cysts: An Observational Study.

Odontogenic cysts are a diverse group of pathologic entities with different proliferation potential, leading to variations in their biological behavior. One of the most cited proliferation markers used in diagnostic histopathology is Ki-67. Another group of proteins recently investigated is minichromosome maintenance (MCM-3) and its expression has been evaluated in several odontogenic lesions but the results were controversial. Thus, the present study endeavored to compare the expression of MCM-3 and Ki-67 in odontogenic cysts. Furthermore, a pioneer attempt was made to evaluate the sensitivity of these markers to inflammation. A total of 101 cases (37 dentigerous cysts, 37 odontogenic keratocysts, and 27 radicular cysts) were included. Immunohistochemical expression of Ki-67 and MCM-3 were investigated using a labeling index (LI). In addition, they were scored for inflammation, followed by correlation with both markers. The data obtained were subjected to statistical analysis ( P <0.05). Overall, a higher LI of MCM-3 than Ki-67 was obtained in all study groups along with a positive correlation of Ki-67 LI with inflammation. Thus, MCM-3 proteins proved to be a more accurate means to determine the proliferation potential and were not sensitive to external stimuli like inflammation than conventional markers, such as Ki-67.

Utility of BRAF V600E immunohistochemistry in the diagnosis of mandibular ameloblastomas.

Ameloblastoma, odontogenic keratocyst (OKC), and dentigerous cyst (DC) can have similar radiographic and histological appearances. The purpose of this study was to determine the utility of BRAF immunohistochemistry in discerning mandibular ameloblastomas from OKCs and DCs. This retrospective cohort study included patients treated between 1998 and 2018. Inclusion criteria include incisional biopsy-proven mandibular ameloblastoma, OKC, or DC, and sufficient tissue for immunohistochemistry. The primary predictor variable was the type of lesion. The primary outcome variable was the presence/absence of BRAF V600E immunoreactivity. The cohort consisted of 43 patients (19 female, 24 male; mean age 48 ± 17 years). There were 22 ameloblastomas, 11 OKCs, and 10 DCs. Among ameloblastomas, 68.2% (15/22) stained positive for BRAF V600E; no OKC or DC was positive (P < 0.001). By subtype, the majority of the follicular (83.3%), unicystic (83.3%), desmoplastic (66.7%), and acanthomatous (100%) subtypes were positive, but only 33.3% of the plexiform subtype were positive. BRAF immunohistochemistry may be a useful adjunct in the differentiation of ameloblastoma from OKCs and DCs on incisional biopsies. It may be particularly useful for small samples with a prominent cystic component or equivocal histopathology. Mandibular lesions that are BRAF immunohistochemistry positive are unlikely to be DCs or OKCs.

Mandibular primary intraosseous carcinoma arising from long-standing odontogenic keratocyst.

Primary intraosseous carcinoma (PIOC) of the jaw is a rare neoplasm arising from the lining epithelium of odontogenic cysts or de novo from odontogenic epithelial rests that has no communication with the surrounding mucosa of the upper aerodigestive tract. We present a case of PIOC ex-odontogenic keratocyst (PIOC ex-OKC) in a 35-year-old male. Histopathologic examination revealed a cystic lesion with a fibrous capsule lined by corrugated parakeratinized stratified squamous epithelium resting on a basal cell layer composed of columnar cells exhibiting palisaded hyperchromatic nuclei, features consistent with OKC. Surgical treatment consisted of bilateral crestal and crevicular incision, a reflection of the flap, breaking of all OKC locules, creation of a continuous cavity, and fitting of a decompression mold around the mandibular teeth. This case highlights the importance of knowing the features of PIOC and considering PIOC in the differential diagnosis of malignant tumors of odontogenic epithelium for timely surgical treatment.

Immunohistochemical Expression of CK14 and Bcl-2 in Odontogenic Keratocyst and Its Variants.

Odontogenic keratocysts (OKCs) are aggressive cystic jaw lesions with a high epithelial turnover rate and increased propensity for recurrence. Sometimes, the characteristic histopathological features of OKCs are either completely lost or seen focally due to previous marsupialization or inflammation. This research aimed to determine whether specific patterns of CK14 and Bcl-2 staining could assist in diagnosing OKCs with altered epithelial features and provide clues in elucidating their aggressive nature. CK14 expression was restricted to basal and suprabasal layers near satellite cysts and in areas showing subepithelial split. The entire epithelial lining showed CK14 expression in areas of inflammation and after marsupialization. The typical basal/suprabasal staining of Bcl-2 was lost in areas of inflammation and intensity is decreased in OKCs after marsupialization. These new findings could offer a hint into the biological nature and pathogenesis of OKCs. Because of its therapeutic consequences and high recurrence rate, proper recognition and diagnosis are essential for treatment planning.

[Surgical removal of an atypically large extensive radicular cyst in the mandible: a case report.] / Atypisch grosse radikuläre Zyste. Operative Entfernung einer atypisch grossen ausgedehnten radikulären Zyste im Unterkiefer, ein Fallbericht.

The radicular cyst is the most common odontogenic cyst and is caused by inflammation. It can become atypically large, although the size of the radiographic osteolysis says nothing about the entity of the lesion. This case shows an unusually large multilocular radicular cyst expanding buccally from tooth 46 in a patient with severe autism who can only be treated under general anesthesia. The clinical and radiological picture as well as the intraoperative situation was more indicative of an aggressive cyst or benign tumor. The lesion was surgically completely removed and the teeth 46, 47 and 48 were extracted because of poor compliance and prognosis. Histopathology revealed a radicular cyst. There were no postoperative complications. After eight months, the lesions had almost completely reossified.