Abstract
<b><i>Introduction:</i></b> Mandibular osteosarcoma (MOS) is a rare malignant bone tumour known for its rapid and aggressive behaviour, particularly in cases of relapse. Early and accurate diagnosis is crucial for effective treatment. <b><i>Case Presentation:</i></b> We report the case of a 48-year-old woman with recurrent MOS. Fine-needle aspiration cytology (FNAC) was utilized for diagnosis, facilitating prompt and appropriate treatment. The FNAC technique proved essential in confirming the diagnosis quickly, allowing for timely intervention. <b><i>Conclusion:</i></b> This case underscores the importance of FNAC in diagnosing MOS, especially in relapse situations where swift treatment is critical. FNAC can be a valuable tool in ensuring rapid and accurate diagnosis, leading to better patient outcomes.