Osteosarcomas of the jaws (OSJ) are difficult to diagnose, rare malignant lesions, with uncharacteristic radiographic and clinical presentation. Early diagnosis and treatment are essential to improve long-term prognosis. The current report presents a rare case of a primary conventional osteoblastic osteosarcoma of the anterior maxilla in a 25-year-old female. She presented to a private dental clinic after developing pain, facial oedema and palpation tenderness of a mass associated with the upper right lateral incisor. The signs and symptoms mimicked very closely a regular radiolucent and symptomatic periapical pathology, and the definitive diagnosis was only possible through a combination of clinical, radiographic and histopathological findings. The patient was referred to an oncology facility, where she was submitted to radical excision surgery through a hemi-maxillectomy. Although other pathologies are uncommon, the differential diagnosis of lesions compatible with odontogenic periapical pathology should not be neglected.