Mandibular Osteosarcoma Presenting as a Benign Odontogenic Lesion: A Case Report

Abstract

Background

Osteosarcoma of the jaws (OSJ) is a rare malignant bone tumor with variable clinical and radiographic presentations, often mimicking benign odontogenic or inflammatory lesions. This diagnostic uncertainty frequently leads to delayed recognition and treatment.

Case

A 29-year-old female presented with a gradually enlarging, painful swelling in the left mandibular region that had been progressing over 3 months. The swelling was associated with tooth mobility. She had previously received treatment for a presumed periapical pathology elsewhere. On radiographic evaluation, including intraoral periapical and occlusal radiographs, orthopantomogram, and cone-beam computed tomography, an ill-defined mixed radiolucent–radiopaque lesion was observed, along with widening of the periodontal ligament space and a characteristic sunburst periosteal pattern. Histopathological analysis revealed a highly cellular malignant neoplasm composed of pleomorphic osteoblast-like cells producing disorganized woven bone, leading to a diagnosis of well-differentiated osteogenic sarcoma of the mandible.

Discussion

OSJ presents significant diagnostic challenges due to its rarity and overlap with common dental conditions. Correlation of clinical features with advanced imaging and histopathology is essential for early diagnosis.

Conclusion

This case emphasizes the need for heightened clinical suspicion when evaluating atypical jaw lesions. Prompt multidisciplinary diagnosis and management are essential to improve outcomes in patients with OSJ.

Introduction

Cancer is still a major cause of death around the world, limiting global average life expectancy. Among tumors of the head-and-neck region, sarcomas account for only about 2% of these lesions.^{1, 2}

Osteosarcoma of the jaws (OSJ) represents a malignant bone tumor characterized by the production of osteoid or immature bone. The tumor is often seen in the mandibular or maxillary region. Patients present with a history of painless jaw swelling, tooth mobility, paresthesia, alterations in occlusion, or trismus. The typical radiographic features are of a mixed radiolucent–radiopaque lesion, while histopathology may be varied; biopsies help to establish the final diagnosis.^3–6

Herein, we describe the case of a patient who presented to the Oral Medicine and Radiology Department.

Case Report

A 29-year-old female patient visited the Department of Oral Medicine and Radiology, with a chief complaint of swelling and pain in the left lower jaw of the face for the past 3 months. The swelling initially presented as a small nodule and gradually progressed to its current size. The patient reported pain that was sudden in onset, intermittent in nature, localized, and non-radiating. There was no history of fever or pus discharge.

On general examination, there was noticeable weight loss with no other systemic disease and no history of any medications. No abnormalities were seen with lymph node examination.

On extraoral examination (Figure 1a), a solitary swelling was noted in the left mandibular region, measuring approximately 2 × 2 cm. The swelling extended anteroposteriorly from the facial midline to the line drawn downwards from the outer canthus of the left eye to the deep border of the mandible posteriorly, and superoinferiorly from the line joining the left corner of the mouth to the line joining the pinna of the ear, inferiorly to the inferior border of the mandible. The overlying skin appeared stretched, while the surrounding skin was normal in appearance. On palpation, all the inspectory findings were confirmed with noted size, shape, and extent. The swelling was hard in consistency, nontender.

Figure 1.

(a) Extraoral Front Facial View Showing Facial Asymmetry Associated with Jaw Osteosarcoma. (b) Solitary Swelling in the Left Mandibular Posterior Region.

The intraoral examination (Figure 1b) revealed a small swelling on the left jaw of the mandible between 33 and 36, extending anteroposteriorly from the distal aspect of 33 to the mesial aspect of 36, superoinferiorly from the free gingival margin to the deep vestibule. It measured approximately 2 × 2 cm. The overlying mucosa appeared erythematous, and the surrounding mucosa appeared to be normal. On palpation, all inspectory findings were confirmed with noted size, shape, and extent. The swelling was hard in consistency and tender.

The patient presented with Grade I mobility in relation to 35.

The vitality of the tooth was not performed in relation to 35

The swelling was provisionally diagnosed as a periapical abscess in relation to tooth 35, and odontogenic cyst and tumor were considered as differential diagnoses by a local dentist, and access opening was performed. As there was no resolution of symptoms, the patient was subsequently referred to a higher center for further evaluation.

Intraoral periapical radiograph (IOPAR) revealed a well-defined radiolucency involving the crown of 35, suggestive of an access opening. In addition, the apical regions of 34 and 35 showed ill-defined mixed radiolucent and radiopaque changes within the alveolar bone, with widening of the PDL space (Figure 2a). On further taking an occlusal radiograph, it revealed radiating spicules of bone extending outwards from the central lesion like rays of the sun, giving a sunburst appearance (Figure 2b).

Figure 2.

(a, b, c) Intraoral Periapical, Occlusal, and Orthopantomogram (OPG) Radiograph Demonstrating an Ill-defined Mixed Radiolucent–Radiopaque Lesion with Periodontal Ligament Space Widening and a Characteristic Sunburst Appearance in the Left Mandibular Region, Suggestive of Osteosarcoma.

Orthopantomogram (OPG) of the patient revealed an ill-defined mixed radiopaque radiolucent lesion in the left mandibular region extending from the distal aspect of the mandibular lateral incisor, involving the body of the mandible. It had ragged borders, with internal structures showing mixed radiopaque–radiolucent areas with a radiating pattern (Figure 2c). Posteroanterior (PA) view of the skull showed similar findings.

Cone-beam computed tomography (CBCT) revealed destruction and expansion of the buccal cortical plate with a mixed radiopaque lesion involving the anterior and left body of the mandible (Figure 3).

Figure 3.

Cone-beam Computed Tomography (CBCT) Axial Section and 3D Volume Image Demonstrating Ill-defined Mixed Radiolucent–Radiopaque Lesion with Cortical Destruction and Irregular Bone Pattern Suggestive of Mandibular Osteosarcoma.

The patient was advised for incisional biopsy of the lesion and was sent for histopathological examination. Sections show a highly cellular neoplasm composed of tumor cells that are round to oval and spindled at places, exhibiting marked nuclear atypia. Cells have hyperchromatic and pleomorphic nuclei with dispersed chromatin, prominent nucleoli and densely eosinophilic cytoplasm, some resembling osteoblasts. Admixed with these are lace-like disorganized woven bone intimately associated with neoplastic cells and osteoclast-like giant cells (Figure 4).

Figure 4.

Histopathological Section Shows Pleomorphic Osteoblast-like Cells Producing Disorganized Woven Bone, Consistent with Well-differentiated Osteogenic Sarcoma.

Considering the histopathological findings in conjunction with the clinical presentation and radiographic features, a final diagnosis of well-differentiated osteogenic sarcoma of the left mandible was established.

Discussion

According to research by Bennett et al., primary OSJ can occur across the age range from 10 to 87 years, with an average onset age of 36.9 years. A slight female predominance has been observed. ⁷

In the mandible, these tumors most commonly affect the horizontal ramus, whereas in the maxilla, preferred locations include the alveolar ridge, the sinus floor, and the palate. ⁵

Pathogenesis

OSJ can develop against the backdrop of various preexisting bone conditions. These include chronic osteomyelitis, fibrous dysplasia, multiple osteochondromas, Paget’s disease, bone infarctions, giant cell tumors, and osteogenesis imperfecta. Additionally, prior exposure to radiation therapy has been linked to the emergence of this malignancy. ⁸

Genomic studies have revealed that osteosarcoma carries a high mutation load and complex chromosomal changes. Key genes often affected include tumor suppressors p53 (mutated in 80%–90% of cases) and RB1 (in 10%–39%), along with others like ATRX, DLG2, RUNX2, and PTEN.^9–11

The immune system plays a vital role in OSJ by influencing tumor growth, spread, and response to treatment. Key immune players include tumor-associated macrophages (TAMs), which promote inflammation and blood vessel formation, and tumor-infiltrating lymphocytes (TILs), like CD8+ cells that attack tumors and CD4+ cells that coordinate immune responses. ¹²

Angiogenesis is usually driven by an excess of pro-angiogenic signals, especially vascular endothelial growth factor (VEGF), which binds to vascular endothelial growth factor receptor (VEGFR) on blood vessel cells, triggering their growth and development. This promotes tumor expansion.^{13, 14}

Case Correlation

In this case, a 29-year-old female with no prior history of significant medical issues, surgeries, or radiation exposure presented with a primary mandibular lesion that exhibited aggressive clinical behavior and radiographic findings.

Imaging

Imaging studies played a vital role in this case by clearly outlining the tumor’s size, location, and the extent of bone destruction. ¹⁵ OSJ may appear entirely osteolytic or as a combination of radiolucent and radiopaque areas on radiographs. One of the earliest signs is the widening of the periodontal ligament space—an appearance that can easily be mistaken for less serious conditions, such as benign odontogenic or inflammatory lesions. ⁶

When the tumor invades the periosteum, it often results in thin, irregular spicules of bone radiating outward, perpendicular to the cortical surface—producing the well-known “sunburst” appearance. Another potential radiographic feature is Codman’s triangle, a triangular elevation of the periosteum. While both of these findings are considered characteristic of osteosarcoma, neither is consistently present nor entirely specific to the disease. ¹⁶

Advanced Imaging Modalities

Computed tomography (CT): CT offers high-resolution, multiplanar, and 3D reconstructed images, which are particularly helpful for assessing the extent of tumor spread both inside and outside the bone. It can also detect small, mineralized tumor components that might be missed on standard X-rays.

Magnetic resonance imaging (MRI) provides detailed images that clearly show how far the tumor has spread within the bone marrow, the size and extent of any associated soft tissue mass, and the relationship of the tumor to nearby anatomical structures. It also helps detect joint involvement, nerve or blood vessel invasion, and aids in defining surgical margins with high precision.^17–19

Positron emission tomography (PET) and dynamic contrast-enhanced MRI (DCE-MRI) are increasingly used in oncology. PET scans measure metabolic activity and are proving to be powerful tools for evaluating tumor aggressiveness, monitoring response to therapy, and detecting metastases. ²⁰

Metastatic Potential

OSJ has a high tendency to spread, most commonly through hematogenous spread. Alarmingly, about 10%–20% of patients already have metastatic disease at the time of diagnosis. The lungs are affected in approximately 80% of these cases, followed by the bones (in 30%–35%) and lymph nodes (around 2%).

The presence of metastases at the initial diagnosis significantly worsens the prognosis. While patients without metastases may have a 5-year survival rate of 60%–70%, those with metastases see this drop drastically to just 10%–30%. ²¹

Biopsy and Diagnostic Markers

A biopsy remains the gold standard for confirming a diagnosis of OSJ. ²² Alongside histological examination, certain biochemical markers, such as serum alkaline phosphatase (ALP) and lactate dehydrogenase (LDH), serve as useful tools for diagnosis, prognosis, and monitoring treatment response. ¹⁶

Recurrence

Recurrence is the most common and challenging complication in OSJ treatment. ¹⁶ Once the cancer returns, the risk of death due to the disease increases sevenfold, underlining the critical need for strict follow-up and aggressive management after initial treatment.

Conclusion

Osteosarcoma of the jaws is an uncommon malignancy that often presents like routine dental disease, which can delay diagnosis. Careful correlation of clinical findings with imaging and histopathology is essential for early identification. Management typically requires a multidisciplinary approach, with surgery and chemotherapy forming the cornerstone of treatment. Given the aggressive nature of the tumor and its tendency to recur, long-term follow-up is crucial. Ongoing advances in genetics and targeted therapies offer hope for improved outcomes in the future.