Radiographic and histopathologic characteristics of simple bone cysts: a retrospective study of 46 cases

Abstract

Objectives

This study aimed to evaluate the clinical, radiographic, and histopathological characteristics of simple bone cysts and to investigate the relationships among these parameters.

Methods

A total of 46 cases diagnosed with SBC were included in this retrospective study, analyzing clinical, radiological, histopathological, and treatment data, as well as recurrence. Radiographic evaluations were performed using panoramic imaging and/or cone-beam computed tomography. Associations among clinical, radiological, and histopathological variables were analyzed using chi-square and Fisher’s exact tests.

Results

The results showed a slight female predilection and a predominant occurrence in the second decade of life. All lesions were located in the mandible, most commonly in the posterior region. Radiographically, lesions were typically unilocular radiolucencies, often with scalloped borders (63.1%) and pseudosepta (56.5%). Histopathologically, fragmented normal bone and fibrous septa were the most frequent findings. Curettage was the most common treatment, and no recurrences were observed. Correlation analyses demonstrated significant associations between multilocular appearance and vascular connective tissue (66.7% vs. 5.9%, p = 0.008), and between lesion size and age, with larger lesions predominantly seen in patients under 20 years, while all patients over 20 years had small lesions (p = 0.002). Although other associations did not reach statistical significance, inflammatory changes were more frequent in symptomatic cases (28.6% vs. 9.4%), and both hemosiderin deposition (25% vs. 10.9%) and vascular connective tissue (21.4% vs. 6.3%) tended to be more common in trauma-associated cases.

Conclusions

SBCs most often present as well-defined, unilocular radiolucencies in the posterior mandible; however, internal variations such as pseudosepta and radiopaque areas may complicate their appearance and highlight the need for careful differential diagnosis from more aggressive lesions. Correlation analyses indicated that multilocular radiographic appearance was linked to vascular connective tissue and lesion size was age-dependent, suggesting that clinical, radiological, and histopathological features are interrelated and should be evaluated together.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-025-07511-z.

Introduction

SBC is a rare, benign intramedullary bone lesion of unknown etiology, characterized by a hollow or fluid-filled cavity lacking epithelial lining [1, 2]. While most commonly observed in the proximal humerus (50%) and femur (25%), SBCs can also occur in the proximal tibia, pelvic bones, calcaneus, spine, and small bones of the hands and feet, particularly in older individuals [3].

In the jaws, SBCs are uncommon, accounting for approximately 1% of all jaw cysts. They occur predominantly in the mandible especially the posterior region while maxillary involvement is exceedingly rare [4]. Historically, various terms—such as traumatic bone cyst, hemorrhagic bone cyst, and unicameral bone cyst—have been used in the literature to describe this lesion. In contemporary WHO terminology, the terms “simple bone cyst” and “solitary bone cyst” are adopted, and the use of other alternative names is no longer recommended [5]. The 1992 WHO Head and Neck Tumour Classification initially placed SBCs under “Neoplasms and Other Bone Lesions.” In the 2017 revision, they were reclassified under “Giant Cell Lesions and Bone Cysts,” and this was retained in the 2022 WHO Classification of Head and Neck Tumours, aligning SBCs within the broader spectrum of jaw pathologies [5] .

SBCs are most frequently diagnosed in young individuals, particularly during the second and third decades of life [1, 6], and are typically asymptomatic-often discovered incidentally during routine dental radiographs [6–9].

Radiographically, SBCs usually appear as unilocular, radiolucent lesions with curved or oval borders [10]. Larger lesions may demonstrate pseudoseptae, although these lack the true characteristics of internal septa. The cortical margin is generally well-defined and thin, yet in some cases may appear indistinct, complicating radiographic detection [7, 11, 12]. Root resorption and tooth displacement are rare findings [1]. Occasionally, SBCs may coexist with other conditions such as cemento-osseous dysplasia (COD) [7, 12].

Histopathologically, SBCs do not exhibit an epithelial lining. Instead, they often contain loosely collagenous or myxoid connective tissue, delicate immature bone fragments, and may feature hemosiderin, cholesterol clefts, or sparse osteoclasts [13].

Although a limited number of studies [14–16] have reported the clinical, radiological, and histopathological features of SBCs, these aspects have typically been presented descriptively and in isolation. To the best of our knowledge, no previous study has statistically analyzed the correlations among clinical, radiological, and histopathological findings within the same SBC patient cohort. Therefore, this study aimed to evaluate the clinical, radiographic, and histopathological characteristics of simple bone cysts and to investigate the relationships among these parameters. By examining these associations in a systematic and integrated manner, the study seeks to contribute to a more holistic understanding of SBCs.

Materials and methods

The study adhered to the guidelines of the Helsinki Declaration, and its protocol was approved by the Clinical Research Ethics Committee of the Faculty of Dentistry at Istanbul University (Protocol number 2024/01 Rev-1).

A total of 46 cases diagnosed with SBC were included in the study from the archives of the Department of Oral Pathology at Istanbul University Faculty of Dentistry between 2012 and 2024. The clinical and histological findings of these cases were evaluated.

The clinical parameters assessed included gender, age, symptoms, history of trauma, vitality of teeth, and the treatment procedures. These clinical parameters were included because they contribute to the differential diagnosis and clinical management of radiolucent jaw lesions and support the integrated evaluation of clinical, radiographic, and histopathological characteristics. Histopathological examination was conducted based on the cyst’s macroscopic volume and microscopic findings.

Radiographic data for the cases diagnosed with SBC were obtained from the archives of the Department of Oral and Maxillofacial Radiology at Istanbul University Faculty of Dentistry. Among these, panoramic radiographs were available for 38 patients, with cone-beam computed tomography (CBCT) images for 23 cases.

Shape classification was performed using panoramic radiographs, categorizing lesions as “ovoid,” “cone,” or “irregular.” Lesions are classified as ‘ovoid’ if they have smooth and rounded contours, as ‘cone’ if they formed an approximate 45-degree angle with the healthy bone, and as ‘irregular’ if they do not fit either of these definitions (Fig. 1).

Fig. 1.

a Ovoid shape with well-defined smooth margins, (b) cone shape indicated by solid arrows and well-defined scalloped margins indicated by dashed arrows, (c) irregular shape with nodefined margins

Sizes were classified into two categories: “equal to or less than three teeth involved,” defined as a small lesion, and “greater than three teeth involved,” defined as a large lesion.

Peripheral characteristics were classified as “well-defined” and “ill defined” with well-defined lesions further evaluated as having “smooth” or “scalloped” contours (Fig. 1).

The internal structure of the lesion was assessed for the presence of pseudosepta and radiopaque masses (Fig. 2). Additionally, the relationship with the mandibular canal and interactions with surrounding anatomical structures were examined through CBCT images (Fig. 2).

Fig. 2.

a Pseudosepta indicated by arrows, (b) radiopaque mass indicated by arrows, (c) intact lamina dura, (d) absent lamina dura, (e) cortical bone expansion indicated by solid arrows and cortical bone destruction indicated by dashed arrows, (f) inferior displacement of the mandibular canal indicated by arrows

Postoperative panoramic radiographs were available for 22 patients, who were followed up for healing and recurrence. The criterion for healing was defined as the formation of new bone trabeculae in the lesion area, while recurrence was indicated by the expansion or reappearance of radiolucency after surgery (Fig. 3).

Fig. 3.

a and (b) are panoramic radiographs of the same patient, showing (a) the SBC lesion and (b) the panoramic view after one year follow-up after enucleation treatment

Radiographs were independently evaluated by two oral and maxillofacial radiologists. In cases of disagreement, a consensus was reached through discussion.

All histological slides were re-examined and evaluated based on the following criteria (Fig. 4):

Fig. 4.

Histopathological image showing a thin, non-specific connective tissue membrane lining a cystic cavity that lacks a true epithelial lining with bone fragments (H&E x40)

1. Bone Tissue Assessment:

• ◦ Presence of normal bone fragments.

• 2.Connective Tissue Analysis:

• ◦ Identification of fibrous connective tissue.

• ◦ Presence of vascular fibrous connective tissue.

• 3.Marrow Evaluation:

• ◦ hematopoietic marrow and/or fatty marrow.

• 4.Vascular and Hemorrhagic Features:

• ◦ Detection of blood extravasation.

• ◦ Identification of intracellular and extracellular hemosiderin deposits.

• 5.Inflammatory and Infectious Indicators:

• ◦ Presence of pus.

• ◦ Evaluation of inflammatory changes.

Although some histopathological features are considered secondary rather than diagnostic criteria, they were systematically evaluated in this study to document the overall histological spectrum and to investigate their potential associations with clinical and radiographic parameters.

In this study, the correlations between clinical (age, sex, symptoms, history of trauma), radiographic (lesion size, multilocular/unilocular appearance), and histopathological (inflammatory changes, vascular connective tissue, marrow type, presence of hemosiderin) variables were evaluated. Age was categorized as < 20 and ≥ 20 years for the analyses. Previous studies have reported that hematopoietic marrow in the mandibular body disappears and is replaced by fatty marrow at the beginning of the second decade of life [17]. Therefore, the age threshold of 20 years was considered appropriate, taking into account both the reported peak incidence of SBC in the second decade and the predominance of mandibular body localization in our study.

All CBCT images were evaluated in consensus by two dentomaxillofacial radiologists with 3 (MTY) and 5 years (RDT) of experience, respectively. Prior to the evaluations, both observers were calibrated by a senior dentomaxillofacial radiologist (HCK). All assessments were performed together during joint sessions, and the final decisions were made collaboratively.

Statistical analysis

Descriptive statistical methods (frequencies and percentages) were used to summarize the data. The Chi-square test was applied to compare categorical variables, and Fisher’s exact test was used when expected cell counts were small. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to estimate the strength and direction of associations. A significance level of p < 0.05 was considered statistically significant.

The required sample size was estimated using a simple random sampling method. Assuming a prevalence of 0.80, a desired precision of ± 0.05, a significance level of α = 0.05, and a statistical power of 95%, the minimum sample size was calculated as 37 after applying the finite population correction for the study population of 46 patients. Since all 46 cases were included in the study, the sample size was considered sufficient to ensure adequate statistical power.

Results

A total of 46 SBC cases were included in the study, and their clinical and radiographic findings are presented in Table 1. Of these cases, 26 (56.5%) were female and 20 (43.5%) were male, with an average age of 23.7 years for females and 18.7 years for males. There was no significant difference in the gender distribution between females and males (p = 0.461).

Table 1.

Clinical data and radiographic features of patients with SBC

CLINICAL DATA (n=46)	n(%)	RADIOGRAPHIC FEATURES	n(%)
Gender		Shape (n=38)
Male	20 (43.5%)	Cone	13 (34.2%)
Female	26 (56.5%)	Ovoid	17 (44.7%)
		Irregular	8 (21.1%)
Age		Size (n=38)
Male		Small lesion	21 (55.3%)
Min-Max	12-48	Large lesion	14 (36.8%)
Mean	18.7	Unknown*	3 (7.9%)
Female
Min-Max	11-45
Mean	23.7
Range	21.5
Age		Margin ( n=38)
2.Decade	32 (69.5%)	Well defined	33 (86.8%)
3.Decade	4 (8.7%)	Scallop margin	24 (63.1%)
4. Decade	5 (10.9%)	Smooth margin	9 (23.7%)
5. Decade	5 (10.9%)	İll defined	5 (13.2%)
Bone involved		Loculi (n=23)
Maxilla	0 (0.0%)	Unilocular	17 (73.9%)
Mandible	(100.0%)	Multilocular	6 (26.1%)
Location		Internal Structure (n=23)
Anterior	12 (26.1%)	Radioopaque mass
Posterior	31 (67.4%)	Present	2 (9.1%)
Ramus	3 (6.5%)	Absent	20 (90.9%)
		Pseudosepta
		Present	10 (43.5%)
		Absent	13 (56.5%)
History of trauma		Displacement of teeth (n=23)
Present	5 (10.9%)	Present	0 (0.0%)
Absent	41 (89.1%)	Absent	20 (87.0%)
		Unknown*	3 (13.0%)
Symptomatology		Root resorption (n=23)
Present	14 (30.4%)	Present	1 (4.4%)
Absent	32 (69.6%)	Absent	19 (82.6%)
		Unknown*	3 (13.0%)
Vitality		Lamina Dura (n=23)
Present	40 (87.0%)	Present	13 (56.5%)
Absent	6 (13.0%)	Absent	4 (17.5%)
		Partly	3 (13.0%)
		Unknown *	3 (13.0%)
Treatment		Relationships between cysts and the mandibular canal (n=23)
Curettage Of The Bone Wall	23 (50.0%)
Enucleation	11 (24%)	Displacement of the mandibular canal	9 (39.1%)
Surgical Excision	6 (13.0%)	In contact with the mandibular canal	8 (34.8%)
Incisional biopsy	6 (13.0%)	No relation to the mandibular canal	6 (26.1%)
Treatment follow-up (n=22)		Bone expansion (n=23)
Recurrence	0 (0.0%)	Present	12 (52.2%)
Healing	22 (100.0%)	Absent	11 (47.8%)

*cases located in the edentulous region

The majority of the cases were observed in the second decade of life, accounting for 69.5% (32 cases) of the total. All cases in our study were located in the mandible, with the highest incidence found in the posterior region (31 cases, 67.4%). Symptoms were present in 14 cases (30.4%), and a history of trauma was identified in 8 cases (17.4%). Among these, one patient experienced trauma associated with orthodontic treatment, while the remaining cases involved direct impact trauma.

Curettage was the most frequently performed treatment (50.0%), followed by enucleation (31.4%) and surgical excision (13.0%). Six cases were left for spontaneous healing. Follow-up radiographs were available in 22 patients, with no recurrences observed during 6 months to 8 years of monitoring.

Lesion shapes were evaluated, revealing that 17 cases (44.7%) were classified as ovoid, while 13 cases (34.2%) exhibited a cone shape. Additionally, 8 cases (21.1%) were identified as irregular.

The size of the lesion was evaluated based on the area affected by neighboring teeth, categorized into two groups: small lesions and large lesions. The majority of cases (21 cases, 55.3%) were classified as small lesions. Among the small lesions, 52.38% were cone-shaped, 38.10% were ovoid, and 9.52% were irregular. In contrast, for the large lesions, 61.54% were ovoid, 7.69% were cone-shaped, and 30.77% were irregular.

The assessment of border structure indicated that the lesions were predominantly well-defined, with 33 cases (86.8%) falling into this category. Among these, scalloped borders were the most commonly observed, seen in 24 cases (63.1%). Ill-defined borders were identified in only 5 cases.

Most of the lesions were unilocular, identified in 17 cases (73.9%). The internal structure of the lesions was predominantly radiolucent, observed in 90.9% of cases, with only 2 cases presenting a radiopaque mass within the cavity. Pseudosepta were noted in 10 cases (43.5%), while no cases exhibited tooth displacement. Root resorption was observed in only 1 case.

Regarding the lamina dura, it was found to be intact in 13 cases (56.5%), absent in 4 cases, and partially present in 3 cases. When assessing the relationship of the cysts with surrounding tissues, mandibular canal displacement was noted in 9 cases (58.9%). Cortical bone expansion was observed in 12 cases (52.2%), while 11 cases (47.8%) showed no expansion. Destruction of cortical bone was seen in 8 cases.

Four cases (11.4%) of SBC associated with COD were observed. Three of these cases were female, aged 39, 45, and 37 years, respectively. The other case was an 18-year-old male patient. Two of these cases were associated with florid cemento-osseous dysplasia (FCOD), while the other two were linked to focal osseous dysplasia (FOD).

Histopathological analysis revealed that all cases (100%) exhibited fragmented normal bone and varying amount of fibrous septa. Hematopoietic marrow was present in 21.74% of cases, while fatty marrow was observed in 17.39%. Vascular fibrous connective tissue with hemangioma-like features was identified in 30.43% of cases. Blood extravasation was noted in 80.43% of the samples, and intracellular or extracellular hemosiderin deposition was detected in 11.42%. Inflammatory changes were observed in 15.2% of cases, whereas no instances of pus formation were recorded (Table 2).

Table 2.

Histopathologic features of 46 SBC cases

Normal bone(fragmented)	46 (100.0%)
Fibrous connective tissue	46 (100.0%)
Hematopoietic marrow	10 (21.74%)
Fatty marrow	8 (17.39%)
Vascular fibrous connective tissue or “hemangioma”	14 (30.43%)
Blood-excuda	37 (80.43%)
Intracellular and extracellular hemosiderin	6 (11.42%)
Pus	0 (0.0%)
Inflammatory changes	7 (15.2%)

Correlation analysis between clinical, radiological, and histopathological parameters is presented in Table 3. A statistically significant association was observed only between multilocular appearance and the presence of vascular connective tissue, which was detected in 66.7% of multilocular cases compared to 5.9% of unilocular cases (OR = 32.0, 95% CI = 2.29–447.85, p = 0.008).

Table 3.

Correlation analysis of SBC parameters

Variable 1	Variable 2		OR (95% CI)	p
	Present (n/N, %)	Absent (n/N, %)
Symptom	Inflammatory changes
Symptomatic	4/14 (28.6%)	10/14 (71.4%)	3.87 (0.73–20.35)	0.176
Asymptomatic	3/32 (9.4%)	29/32 (90.6%)
Multilocular appearance	Vascular connective tissue
Multilocular	4/6 (66.7%)	2/6 (33.3%)	32.0 (2.29-447.85)	0.008
Unilocular	1/17 (5.9%)	16/17 (94.1%)
Gender	Hematopoietic marrow
Female	6/26 (23.1%)	20/26 (76.9%)	2.70 (0.48–15.11)	0.435
Male	2/20 (10.0%)	18/20 (90.0%)
Gender	Fatty marrow
Female	6/22 (27.3%)	16/22 (72.7%)	3.38 (0.59–19.16)	0.243
Male	2/20 (10.0%)	18/20 (90.0%)
History of trauma	Hemosiderin
Present	1/4 (25.0%)	3/4 (75.0%)	2.73 (0.24–31.56)	0.411
Absent	5/46 (10.9%)	41/46 (89.1%)
History of trauma	Vascular connective tissue
Present	3/14 (21.4%)	11/14 (78.6%)	4.09 (0.60-27.85)	0.157
Absent	2/32 (6.3%)	30/32 (93.7%)
Age group	Hematopoietic marrow
≤ 20 years	6/32 (18.8%)	26/32 (81.2%)	1.38 (0.23–8.19)	1.000
> 20 years	2/14 (14.3%)	12/14 (85.7%)
Age group	Fatty marrow
≤ 20 years	4/36 (11.1%)	32/36 (88.9%)	0.44 (0.09–2.11)	0.418
> 20 years	4/18 (22.2%)	14/18 (77.8%)
Age group	Lesion size
≤ 20 years	14/25 (56.0%)	11/25 (44.0%)	0.02 (0.001–0.34)	0.002
> 20 years	0/10 (0.0%)	10/10 (100.0%)

Bolded values indicate statistically significant differences at p < 0.05 level

No other associations reached statistical significance; however, several positive trends were observed. Inflammatory changes were more frequent in symptomatic than in asymptomatic cases (28.6% vs. 9.4%; OR = 3.87, 95% CI = 0.73–20.35, p = 0.176). Hemosiderin deposition was found in 25% of trauma-associated cases compared to 10.9% of cases without trauma (OR = 2.73, 95% CI = 0.24–31.56, p = 0.411), and vascular connective tissue was more common in trauma-associated cases (21.4% vs. 6.3%; OR = 4.09, 95% CI = 0.60–27.85, p = 0.157).

With respect to age, hematopoietic marrow was identified in 18.8% of patients aged ≤ 20 years and 14.3% of those aged > 20 years (OR = 1.39, 95% CI = 0.24–8.15, p = 1.000). Fatty marrow was observed in 11.1% of cases aged ≤ 20 years and 22.2% of those aged > 20 years (OR = 0.43, 95% CI = 0.10–1.91, p = 0.409). Regarding gender, hematopoietic marrow was found in 23.1% of females and 10.0% of males (OR = 2.70, 95% CI = 0.48–15.11, p = 0.435), while fatty marrow was seen in 27.3% of females compared to 10.0% of males (OR = 3.38, 95% CI = 0.59–19.16, p = 0.243).

Among patients younger than 20 years, 11 cases (44%) presented with small lesions, while 14 cases (56%) exhibited large lesions. In contrast, all patients over the age of 20 (n = 10; 100%) presented exclusively with small lesions, and no large lesions were observed in this group. A significant difference was found in lesion size between age groups: smaller lesions were significantly more common in patients over 20 years old, whereas larger lesions were more frequently observed in patients under 20 years (p = 0.002) (Table 3).

Discussion

The etiology of SBCs has long been a subject of debate, and no definitive conclusion has been reached. One of the most widely accepted explanations is the traumatic-hemorrhagic theory, which suggests that hemorrhage within the bone marrow following trauma fails to organize and subsequently leads to the formation of a cystic cavity [4, 10]. However, reported rates of trauma history vary considerably across studies, and opinions regarding this theory remain inconsistent. For example, Lima et al. [1] documented a history of trauma in only 11.7% of cases, while Wang et al. [9] reported an even lower rate of 5.71%. Although SBCs are also commonly observed in the humerus and other long bones, the orthopedic literature does not recognize trauma as an etiological factor. Moreover, there is no evidence indicating an increased incidence of SBCs among boxers or individuals frequently exposed to trauma in the head and neck region [10]. In our series, trauma was identified in only five cases (8.6%).

Besides trauma, several alternative hypotheses have been suggested regarding the etiology of SBCs. These include vascular abnormalities, tumor degeneration, and osteoblastic dysfunctions [17, 18]. Mechanical factors such as chronic occlusal trauma, orthodontic treatment, and malocclusion have also been associated with SBC formation, particularly in the mandible [9, 10].

The possible role of orthodontic treatment was first highlighted by Velez et al. [10], who proposed that orthodontic forces may contribute to the development of SBCs through both biochemical and mechanical mechanisms. Mechanical stress induced by orthodontic forces can stimulate the release of biochemical mediators such as vascular endothelial growth factor (VEGF) and tumor necrosis factor alpha (TNF-α), which promote bone resorption by activating osteoclasts. Additionally, the piezoelectric effect generated on the bone surface during orthodontic movement may alter bone growth, remodeling, and resorption. In our series, one of the five cases with trauma history was associated with orthodontic treatment. Taken together, these findings suggest that SBCs may have a multifactorial etiology, with trauma representing only one of several possible contributing factors [10].

SBCs predominantly affect young individuals and are most commonly observed during the second and third decades of life [1, 6]. In our series, patient ages ranged from 11 to 48 years, with mean ages of 21.5 years for females and 18.7 years for males.The age distribution in our series is consistent with the existing literature, which reports a higher frequency of SBCs in younger individuals.

The literature presents diverse opinions regarding gender distribution in SBC. Some studies [4, 12, 19, 20] indicate that gender distribution is approximately equal, while others report a female predominance [6] or a male predominance [21]. In our analysis of 46 SBC cases, we found that 56.5% of the patients were female and 43.5% were male. Although female patients were more prevalent, this difference was not statistically significant, supporting the notion of equal gender distribution.

In our study, all 46 cases were located in the mandible, with none found in the maxilla. Notably, 67.4% of these lesions were situated in the posterior region of the mandible, a finding consistent with results reported in the existing literature [1, 2, 9, 22].

Clinical symptoms such as pain or swelling were observed in 30.4% of cases in our study, which aligns closely with the findings of Wang et al. [9], who reported symptoms in 31.43% of SBC patients. However, other studies have highlighted a predominance of asymptomatic presentations. For example, Bonjardim Lima et al. [1] noted that fewer than 20% of patients exhibited symptoms, emphasizing that most SBCs are discovered incidentally during routine radiographic evaluations. Overall, our findings support the view that although SBCs can present with symptoms, they are more commonly detected as incidental findings.

Radiographically, SBCs are most commonly characterized as unilocular, radiolucent lesions located in the posterior mandible, often exhibiting smooth borders and scalloping between the roots of adjacent teeth [1, 10, 11]. Beyond the premolar–molar region, the anterior mandible and the ramus are also frequently involved sites [1]. Additionally, although rare, SBCs have been documented in the mandibular condyle and the hyoid bone [20, 23–25]. Maxillary involvement, on the other hand, remains exceptionally uncommon [4]. Seo-Young An et al. [26] suggest that this rarity may be due to the radiolucent nature of the maxillary sinus, which may obscure the radiographic visibility of lesions in that region. Conversely, Martins-Filho et al. [21] propose that the slower healing rate of the dense cortical bone in the mandible compared to the maxilla could explain the higher frequency of SBCs in the mandible, consistent with the trauma–hemorrhage theory.

SBC sizes in the literature are reported to range from 1 to 10 cm [4, 6, 27]. Jihye Ryu et al. [28] classified lesions as ‘small’ if they involved three or fewer teeth, finding this classification applicable to 77.8% of their cases. In our study, we observed that 55.3% of the lesions were small.

A statistically significant association was also observed between lesion size and age, with larger lesions being more prevalent in patients under 20 years of age compared to older individuals. This finding is consistent with the observations reported by Jihye Ryu et al. [28]. The age-related difference in lesion size may suggest that SBCs have the potential to undergo spontaneous regression or size reduction over time.

In a study conducted by Maria A. Copete in 1998 [8], SBCs were categorized based on their morphological appearance on panoramic radiographs, with approximately two-thirds of the lesions described as cone-shaped. Copete further observed that larger lesions predominantly exhibited a cone-shaped morphology, whereas smaller ones tended to appear irregular or ovoid in form. In contrast, our study demonstrated a different pattern of distribution. Ovoid shapes were the most prevalent (44.7%), with larger lesions more frequently presenting as ovoid and smaller ones as cone-shaped.

A more recent investigation by Yahui Wang et al. [9] reported that 74.29% of lesions were round in shape, while 25.71% were classified as irregular. In our sample, 44.7% of the lesions were ovoid, 34.2% cone-shaped, and 21.1% irregular. Notably, ovoid-shaped lesions were more commonly associated with larger sizes, contrasting with the findings reported by Copete [8].

In the literature, well-defined lesion margins have frequently been emphasized as a characteristic feature of SBCs. For instance, You et al. [27] reported a high prevalence of well-demarcated bone cysts, while So-Young Choi et al. [2] similarly noted that most mandibular SBCs exhibit sharp and distinct borders. Clinically, well-defined margins are important as they facilitate accurate identification of the lesion and enable complete surgical excision. Consistent with these findings, our study demonstrated that 86.8% (n = 33) of the lesions exhibited well-defined margins, whereas 13.2% (n = 5) lacked this radiographic feature.

Among the 33 patients with well-defined margins, 24 (63.1%) displayed scalloped margins, while 9 (23.7%) had entirely smooth margins. The upper border of the cyst extends towards the roots of the teeth, forming a ‘fan’-like shape known as scalloping. This characteristic reflects the relationship between the lesion and the adjacent teeth, serving as an important finding in the radiographic diagnosis of SBCs [11].

Typically, the internal structure of SBCs is entirely radiolucent; however, septum-like structures can be observed in posterior regions and in larger lesions [11]. These structures, referred to as pseudosepta, are not true septa [11]. Despite their significance, studies focusing on pseudosepta in the literature are limited. A recent study by Zhe-Yi Jiang and colleagues [29] highlighted the presence of pseudosepta, emphasizing that these structures can give the appearance of multilocular lesions. This condition is crucial for the differential diagnosis of other cysts and tumors with a multilocular appearance and should be considered a critical factor in surgical planning. In our study, pseudosepta were observed in 43.5% of our patients.

In the study by Y. Suei et al. [30] radiopaque masses distinct from periapical osteosclerosis were identified in 8 cases, with recurrence observed in 6 of them following treatment. In our study, radiopaque masses within the internal structure of the lesion were noted in 2 patients, suggesting the possibility of an SBC that may have entered a spontaneous healing process. However, as we were unable to follow up with these 2 patients postoperatively, recurrence could not be assessed.

In our study, inferior displacement of the mandibular canal was noted in 39.1% of patients, which aligns with findings in the literature [1]. Additionally, cortical bone enlargement was observed in 52.2% of our cases, supporting the notion that SBCs generally represent slow-growing, expansive lesions. Various rates of cortical bone destruction in SBCs have been reported in the literature, ranging from 3.84% to 72.7% [1]. The low cortical bone destruction rate of 17.4% observed in our study suggests that SBC’s generally follow a benign course and tend to enlarge gradually.

The literature frequently emphasizes that tooth displacement is rare in cases of SBCs [11], and in our study, we found no instances of tooth displacement [11]. However, some studies, such as those by Forssell [31] and P. F. Perdigão [32], have reported occurrences of tooth displacement in SBC cases. Similarly, root resorption is infrequently noted in the literature [11], and our study identified root resorption in only one case. The lamina dura was intact in 13 patients, partially preserved in 3, and absent in 4. Two patients with lesions in edentulous areas were excluded from this evaluation. These findings are largely consistent with existing literature and show similar results.

The co-occurrence of SBCs with CODs suggests that disruption of intraosseous microvasculature and subsequent hemorrhage may play a contributory role in SBC pathogenesis [7]. Additionally, hormonal or biochemical alterations affecting bone metabolism have been proposed to influence this association, particularly in cases of FCOD [10]. These lesions are most frequently observed in older women, with Chadwick et al. [12] reporting that 87% of cases occurred in females, highlighting the rarity of such presentations in males [1, 7, 10]. In our study, four SBC cases were found to be associated with CODs—two with FCOD and two with FOD. Of these, three patients were female with a mean age of 40 years, while one was an 18-year-old male. The occurrence of COD-associated SBC in such a young male is notably uncommon and may point to the involvement of additional factors beyond gender, such as age-related bone remodeling or vascular dynamics. These findings underscore the need for further research to elucidate the underlying mechanisms of COD-associated SBCs.

Our study is the first to systematically evaluate the correlations among clinical, radiographic, and histopathological parameters in SBCs. This multifaceted approach highlights the heterogeneous and clinically nonspecific nature of SBCs and contributes novel insights into their biological variability.

The most notable finding was the significant association between multilocular appearance and the presence of vascular connective tissue. Vascular content was observed in nearly two-thirds of multilocular cases, whereas it was present in only 6% of unilocular cases (OR = 32). This strong correlation emphasizes the clinical importance of multilocular morphology in surgical planning and further suggests that vascular lesions such as intraosseous hemangiomas—histologically characterized by endothelial cell proliferations forming vascular spaces within a fibrous stroma—should be considered in the differential diagnosis. This overlap indicates that multilocular SBCs may warrant particular caution during surgery due to the potential risk of intraoperative bleeding.

Hemosiderin deposition and vascular connective tissue were also more frequently observed in patients with a history of trauma. Although these differences did not reach statistical significance, they reflect an approximately 2.7-fold and 4-fold increase, respectively. The increased presence of hemosiderin in trauma-associated cases supports the intramedullary hemorrhage theory, which proposes that trauma-induced hematoma formation followed by impaired circulation may lead to bone resorption and cystic cavity development [33]. If confirmed in larger cohorts, these patterns may enhance our understanding of the etiopathogenesis and symptomatology of SBCs.

Although other associations were not statistically significant, several trends were noteworthy. Inflammatory changes were nearly four times more common in symptomatic cases than in asymptomatic ones (28.6% vs. 9.4%; OR = 3.87), suggesting a possible link between inflammatory activity and clinical presentation.

Age- and gender-related analyses indicated biological tendencies in the histological composition of SBCs. Hematopoietic marrow was more frequently observed in younger patients, consistent with the physiological conversion of medullary spaces into fatty marrow with increasing age. In the MRI-based study by Miho Yamada et al. [17], it was reported that the mandible in children, particularly those under 10 years of age, is largely filled with hematopoietic marrow, which gradually converts to fatty marrow following a sequential pattern (mandibular body → angle → condyle) [17]. In our series, the predominance of cases located in the mandibular body and occurring mainly in the second decade of life may also reflect this physiological conversion. These findings suggest that the age distribution and localization of SBCs could be associated with marrow conversion patterns in the mandible.

Differential diagnosis with other bone lesions is crucial because simple SBC’s, which are rare in the jaws, typically present asymptomatically and are often discovered incidentally during routine radiographic examinations [1, 4, 6, 7, 28]. The differential diagnosis of SBCS should include various bone lesions, such as odontogenic keratocysts, radicular cysts, lateral periodontal cysts, central giant cell granulomas, aneurysmal bone cysts, ameloblastomas, cherubism, odontogenic myxomas, focal osteoporotic bone marrow defects, and fibrous dysplasia [4, 17, 26, 28].

SBCs show similarities with odontogenic keratocysts and odontogenic myxomas in their tendency to grow along the bone; however, they can be distinguished by the more prominent peripheral cortical border of odontogenic keratocysts and the characteristic tennis-racket-like septa of odontogenic myxomas [11, 27, 32]. Lateral periodontal cysts and radicular cysts may be confused with SBCs when they appear unilocular and radiolucent [34]. However, lateral periodontal cysts tend to displace teeth, while radicular cysts are typically associated with a non-vital tooth [34]. These distinguishing features help differentiate these lesions from SBC’s. Ameloblastoma, aneurysmal bone cysts, and central giant cell granulomas can present in unilocular and radiolucent forms, which may be confused with SBCs; however, these lesions are distinguished by their greater tendency to expand [11, 27, 32].Multiple SBCs may be confused with cherubism, especially when the lesions are bilateral. In such cases, cherubism should be considered in the differential diagnosis. Furthermore, SBCs in the healing phase may present with a ground-glass radiographic appearance, which can lead to confusion with fibrous dysplasia [11]. A large focal osteoporotic bone marrow defect may be confused with SBC, but focal osteoporotic bone marrow defects tend to occur in edentulous areas [35]. Additionally, the scalloped border structure of SBC is an important feature for distinguishing it from this defect [9, 11, 27, 32]. Detailed information regarding the differential diagnosis is presented in Table S1 (see Supplementary Material).

In the treatment SBCs, the most commonly adopted approach in the literature is surgical evacuation of the lesion followed by curettage. The primary aim of curettage is to induce bleeding within the cavity, thereby initiating bone regeneration through clot formation and accelerating the healing process [26]. Similarly, Sukhvinder Bindra [4], Paulo Ricardo Saquete Martins-Filho [21], and Chrcanovic et al. [18] have reported that curettage facilitates rapid healing and that recurrence rates tend to be higher in cases where no surgical intervention is performed.

On the other hand, divergent views also exist regarding the management of SBCs, with some researchers advocating for the lesion’s potential to heal spontaneously. For instance, in a 2017 study by Maíra de Paula Leite Battisti [36], it was suggested that SBCs can resolve without surgical intervention when monitored through non-invasive clinical and radiographic follow-up, and thus a conservative approach was recommended. However, other authors have emphasized the limitations of this strategy, including the risk of misdiagnosis and the inability to fully assess the lesion’s true nature. Indeed, Isidoro Cortell-Ballester et al. [6] argued that although spontaneous resolution may occur in certain cases, a wait-and-see approach is not advisable due to potential diagnostic uncertainty and complications such as pathologic fractures. In this context, surgical intervention is considered not only as a therapeutic measure but also as a valuable tool for achieving diagnostic clarity. As highlighted in the study by Jihye Ryu [28], surgical exploration enables the exclusion of other pathologies, offering a significant advantage in clinical decision-making.

In our study, curettage was the most frequently performed treatment modality, applied in 50% of cases, followed by enucleation in 24% of cases. Furthermore, no recurrence was observed in any of the 22 patients who were followed postoperatively, reinforcing the efficacy and reliability of the surgical approach. Taken together, the current literature and our findings support that surgical intervention is not only an effective treatment method but also contributes to diagnostic certainty in the management of SBCs.

Strengths and limitations

This study has several strengths. Most importantly, it is the first to comprehensively investigate the correlations among clinical, radiographic, and histopathological features of SBC in the jaws. The inclusion of 46 cases, which represents a relatively large cohort for this rare lesion, provides a solid foundation for analysis. The use of both panoramic radiography and CBCT enabled a more precise assessment of lesion morphology, borders, and internal variations such as pseudosepta and radiopaque components, which are relevant for differential diagnosis. In addition, the integration of clinical parameters (age, sex, symptoms, trauma history), radiographic features, and histopathological findings offers a more comprehensive view of the condition and may contribute to a better understanding of its diverse presentations.

This study also has certain limitations. Its retrospective design restricted the availability of some clinical and follow-up data, which limited the ability to evaluate long-term outcomes in all cases. Although the sample size is relatively large for a rare jaw lesion, it may still be insufficient for more detailed subgroup analyses. Furthermore, the single-center setting may slightly limit the generalizability of the findings. Future multicenter prospective studies with larger cohorts and extended follow-up periods would be valuable to confirm and expand upon these observations.

Conclusion

In conclusion, this study is the first to investigate the correlations among clinical, radiological, and histopathological features of SBCs, providing a more integrated understanding of their diagnostic profile. Consistent with previous reports, most SBCs were located in the posterior mandible and appeared as well-circumscribed, unilocular, radiolucent lesions. The declining relevance of the trauma-hemorrhage hypothesis is supported by our finding that only a small proportion of patients had a trauma history. Additionally, variations in internal structures, such as pseudosepta and radiopaque content, suggest that SBCs may have a more complex radiographic appearance than previously appreciated. Notably, our correlation analysis revealed a significant association between multilocular radiographic appearance and vascular connective tissue, underscoring the importance of considering vascular content in multilocular lesions during differential diagnosis and surgical planning.

Abbreviations

CBCT

Cone-beam computed tomography

CI

Confidence interval

COD

Cemento-osseous dysplasia

FCOD

Florid cemento-osseous dysplasia

FOD

Focal osseous dysplasia

OR

Odds ratio

SBC

Simple bone cyst

WHO

World Health Organization

Authors’ contributions

Concept – HCK, MST; Design – HCK, MST; Supervision – HCK, MST; Materials – MTY; Data Collection and/or Processing – MTY, RDT; Analysis and/or Interpretation – MTY, RDT; Literature Search – MTY; Writing – MTY, RDT; Critical Reviews – HCK, MST. All authors read and approved the final manuscript.

Funding

This study did not receive any external funding.

Data availability

The data supporting the findings of this study are available from the corresponding author upon reasonable request.

Declarations

Ethics approval and consent to participate

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. This study was approved by the local ethics committee (Istanbul University Faculty of Dentistry; Date: 30/01/2024 Number: 162).

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.